Method for printing objects having laser-induced graphene (lig) and/or laser-induced graphene scrolls (ligs) materials

ABSTRACT

Laser-induced graphene (LIG) and laser-induced graphene scrolls (LIGS) materials and, more particularly to LIGS, methods of making LIGS (such as from polyimide (PI)), laser-induced removal of LIG and LIGS, and 3D printing of LIG and LIGS using a laminated object manufacturing (LOM) process.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/312,837, filed Dec. 21, 2018, entitled “Laser-Induced Graphene (LIG)And Laser-Induced Graphene Scrolls (LIGS) Materials” which is the 35U.S.C. § 371 national application of International PCT Application No.PCT/US17/38574, filed on Jun. 21, 2017, entitled “Laser-Induced Graphene(LIG) And Laser-Induced Graphene Scrolls (LIGS) Materials,” whichdesignated the U.S., and which claims priority to U.S. Patent Appl. Ser.No. 62/352,744, filed Jun. 21, 2016, entitled “Laser-Induced GrapheneNanoscrolls (LIGS) From Polyimide (PI),” which patent application iscommonly owned by the owner of the present invention.

This application is also related to PCT Patent Application No.PCT/US2015/062832, filed on Nov. 27, 2015, entitled “Laser InducedGraphene Hybrid Materials For Electronic Devices,” (which published asPCT Patent Publ. No. WO/2016/13351 on Aug. 25, 2016) (“the Tour '351 PCTapplication”) and PCT Patent Application No. PCT/US2015/016165, filed onFeb. 17, 2015, entitled “Laser Induced Graphene Materials And Their UseIn Electronic Devices,” (which published as PCT Patent Publ. No.WO/2015/175060 on Nov. 19, 2015) (“the Tour '060 PCT a”).

These patent applications are hereby incorporated by reference in theirentirety for all purposes.

GOVERNMENT INTEREST

This invention was made with government support under Grant Nos.FA9550-14-1-0111 and FA9550-12-1-0035, awarded by the United StatesDepartment of Defense/Air Force Office of Scientific Research. Thegovernment has certain rights in the invention.

FIELD OF INVENTION

The present invention relates to laser-induced graphene (LIG) andlaser-induced graphene scrolls (LIGS) materials and, more particularlyto LIGS, methods of making LIGS (such as from polyimide (PI)),laser-induced removal of LIG and LIGS, and 3D printing of LIG and LIGSusing a laminated object manufacturing (LOM) process.

BACKGROUND OF INVENTION

The discovery of carbon based nanomaterials such as the fullerenes[Kyoto 1985], carbon nanotubes (CNTs) [Iijima 1991], and graphene[Novoselov 2013] has led to large investments in carbon-basednanotechnology research. Carbon nanomaterials have been extensivelystudied, revealing their outstanding chemical, physical, electrical,mechanical, optical, and thermal properties, many of which are notpossible to achieve using other materials [De Volder 2013; Zhang 2013;Jariwala 2013; Baughman 2002; Allen 2009]. Because of theirextraordinary performances, these carbon nanomaterials have been widelyused in numerous applications such as in transistors [Cao 2013; Liu2014; Schweirz 2010; Heinze 2002], biological and chemical sensors [Shao2010; Rodrigo 2015], energy generation/storage devices [Ren 2013;Habisreutinger 2014; Bonaccorso 2015; El-Kady 2013; Yoo 2008; Kaempgen2009], and polymer nanocomposites [Mittal 2015; Hu 2014].

In order to fully realize their potential in different applications,various derivatives and morphologies of these carbon nanomaterials havebeen developed such as graphene oxide (GO) [Marcano 2010], verticallyaligned CNTs [Hata 2004], and graphene nanoribbons (GNRs) [Kosynkin2009]. Additionally, synthesis of these carbon nanomaterials frominexpensive precursors [Yan 2012] using cost-effective processes [Yan2011] is highly desired for industrial production. Recently, inventorsof the present invention developed a simple and effective method to makeporous graphene from commercial available polyimide (PI) sheets by laserinduction under ambient conditions [Lin 2014]. In these studies, theresulting product, laser-induced graphene (LIG), was found to containfew-layer graphene with high electrical conductivity, high thermalstability, high thermal conductivity [Smith 2016] and outstandingelectrochemical performance. Wetting properties of LIG can be alternatedfrom superhydrophobic to superhydrophilic by conducting the laserprocess under different controlled atmospheres [Li 2017]. A majorapplication of LIG is for microsupercapacitors (MSCs) that have anin-plane interdigitated shape or sandwiched structure [Peng 2015 A]. Thecapacitance of the first generation of LIG-MSCs was 4 mF/cm², comparableto other carbon based MSCs. Follow-up studies increased the capacitanceto 16 mF/cm² by the use of a solid-state electrolyte and boron doping[Peng 2015 B]. Additional research introduced pseudocapacitive materialsinto LIG devices by electrochemical deposition, and the capacitancevalue further increased to 950 mF/cm² [Li 2016]. Another application ofmetal-salt-containing PI films resulted in LIG that contained metaloxide nanoparticles suitable as oxygen reduction reaction (ORR)catalysts [Ye 2015].

Before the development of LIG, carbonization of PI was shown to afford aporous structure by ultraviolet exposure [Schumann 1991; Srinivasan1994], but graphene was not disclosed and there have been no studies onthe parameters required to afford the various possible morphologies.Accordingly, a desire for parameters for the controlled formation ofvarying LIG morphologies remains.

SUMMARY OF INVENTION

A new form of LIG nanomaterials, namely, laser-induced graphene scrolls(“LIGS”), has been discovered. The present invention also relates tomethods of making LIGS (such as from polyimide (PI)).

The present invention further relates to a new process for laser-inducedremoval of LIG, partially or completely, such as with 50 W 1.06 μmwavelength fiber laser.

The present invention further relates to a new process for 3D printingof LIG and LIGS using a laminated object manufacturing (LOM) process.

In general, in one embodiment, the invention features a method thatincludes exposing a graphene precursor material to a laser source toform laser-induced graphene scrolls (LIGS) material. The LIGS materialis derived from the graphene precursor material.

Implementations of the invention can include one or more of thefollowing features:

The graphene precursor material can include a polymer.

The polymer can be selected from a group consisting of polymer films,polymer fibers, polymer monoliths, polymer powders, polymer blocks,optically transparent polymers, homopolymers, vinyl polymers,chain-growth polymers, step-growth polymers, condensation polymers,random polymers, ladder polymers, semi-ladder polymers, blockco-polymers, carbonized polymers, aromatic polymers, cyclic polymers,doped polymers, polyimide (PI), polyetherimide (PEI), polyether etherketone (PEEK), polyamide (PA), polybenzoxazole (PBO), polyaramids, andpolymer composites and combinations thereof.

The polymer can include polyimide.

The step of exposing can include tuning one or more parameters of thelaser source.

The tuning of the one or more parameters of the laser source can includemodifying the laser wavelength so that the laser wavelength is at anabsorption band of the graphene precursor material.

The one or more parameters of the laser source can be selected from agroup consisting of laser wavelength, laser power, laser energy density,laser pulse width, gas environment, gas pressure, gas flow rate,direction of gas flow relative to the lasing head, and combinationsthereof.

The laser source can be a CO₂ laser source.

The laser source can have a wavelength ranging from about 20 nm to about100 μm.

The laser source can include near-field scanning optical microscopy.

The laser source can include a laser having a beam that is diffused witha lens or series of lenses.

The laser can have a high powered beam that can cover an exposed areathat is a large area or line such that the diffused energy has a fluencecapable to form the LIGS over the entire exposed area.

The laser having the high powered beam can be at least a 1 MegaWattlaser.

The laser source can have a power ranging from about 1 W to about 100 W.

The polymer can include a doped polymer.

The doped polymer can include a dopant selected from a group consistingof heteroatoms, metals, metal oxides, metal chalcogenides, metalnanoparticles, metal salts, organic additives, inorganic additives,metal organic compounds, and combinations thereof.

The polymer can include a boron doped polymer.

The LIGS material can be a porous material.

The LIGS material can include a doped LIGS material.

The doped graphene can include a dopant selected from a group consistingof heteroatoms, metals, metal oxides, metal nanoparticles, metalchalcogenides, metal salts, organic additives, inorganic additives, andcombinations thereof.

The laser source can have a laser fluence of at least about 20 J/cm².The laser source can have a wavelength of at least about 9.3 μm.

The laser source can have a laser fluence of more than about 40 J/cm².The laser source can have a wavelength of at least about 10.6 μm.

The laser source can have a laser fluence of more than about 40 J/cm².

The laser fluence can be from about 40 J/cm² to about 200 J/cm².

The laser fluence can be from about 80 J/cm² to about 170 J/cm².

The LIGS material can have a thickness of at least about 20 μm.

The thickness of the LIGS material can be at least about 30 μm.

The thickness of the LIGS material can be at least about 100 μm.

The thickness of the LIGS material can be at least about 500 μm.

The thickness of the LIGS material can be at least about 1 mm.

The LIGS material can include nanoscrolls of graphene having an averagediameter in a range from about 10 nm to about 500 nm.

The average diameter can be in the range from about 20 nm to about 100nm.

The laser source can have a wavelength in the range between 9 μm and 11μm.

The LIGS material can be formed in a one-step laser thermolysis processat a radiation level of at least about 20 J/cm².

The LIGS material can be formed in a one-step laser thermolysis processat a radiation level of at least about 40 J/cm².

The laser source can be being operable above its critical fluence pointneeded to initiate carbonization of the graphene precursor material.

The critical fluence point of the laser can be at least about 5 J/cm².

The laser source can have a wavelength at least about 10.6 μm and acritical fluence point at least about 4.9 J/cm².

The laser source can have a wavelength at least about 9.3 μm and acritical fluence point at least about 2.1 J/cm².

The laser source can be a laser that is being operated in raster mode.

The laser source can be a laser that is being operated in vector mode.

The laser source can have a pulse density such that the pulses do notoverlap.

The method can further include a step of incorporating the LIGS materialinto an electronic device.

The electronic device can include an electrode comprising the LIGSmaterial.

The electronic device can be a flexible electronic device.

The electronic device can be an energy storage device or an energygeneration device.

The electronic device can be selected from a group consisting ofsupercapacitors, micro-supercapacitors, pseudo capacitors, batteries,micro batteries, lithium-ion batteries, sodium-ion batteries,magnesium-ion batteries, electrodes, conductive electrodes, sensors,lithium ion capacitors, photovoltaic devices, electronic circuits, fuelcell devices, thermal management devices, biomedical devices, andcombinations thereof.

The electronic device can be a micro-supercapacitor.

The step of incorporating can include stacking a plurality of LIGSmaterials. The stacking can result in formation of a vertically stackedelectronic device.

The step of incorporating can result in formation of at least one ofvertically stacked electronic devices, in-plane electronic devices,symmetric electronic devices, asymmetric electronic devices, andcombinations thereof.

The LIGS material can be utilized as at least one of an electrode,current collector, or additive in the electronic device.

The method of claim 43 can further include a step of associating theelectronic device with an electrolyte.

The electrolyte can be selected from a group consisting of solid stateelectrolytes, liquid electrolytes, aqueous electrolytes, organic saltelectrolytes, ion liquid electrolytes, and combinations thereof.

The electrolyte can be a solid state electrolyte.

In general, in another embodiment, the invention features a materialthat includes a plurality of concentric nanoscrolls of graphene.

Implementations of the invention can include one or more of thefollowing features:

The nanoscrolls of graphene can have an average diameter in a range fromabout 10 nm to about 500 nm.

The average diameter can be in the range from about 20 nm to about 100nm.

In general, in another embodiment, the invention features a LIGSmaterial made by a method set forth above.

In general, in another embodiment, the invention features an electronicdevice made by a method set forth above.

In general, in one embodiment, the invention features a method thatincludes selecting a laser-induce material selected from a groupconsisting of laser-induced graphene (LIG) materials, laser-inducedgraphene scrolls (LIGS) materials, and combinations thereof (LIG/LIGSmaterials). The method further includes exposing the laser-inducedmaterial to a first laser source having a first wavelength to remove afirst portion of LIG or LIGS from the laser-induced material.

Implementations of the invention can include one or more of thefollowing features:

The laser-induced material can be formed by exposing a grapheneprecursor material to a second laser source having a second wavelength.The first wavelength and the second wavelength can be different.

The first wavelength can be less than 2 μm. The second wavelength can begreater than 5 μm.

The removal of the first portion of the LIG or LIGS from thelaser-induced material can be performed in a predetermined pattern.

The method can further include re-exposing the laser-induced material tothe first laser source to remove a second portion of the LIG or the LIGSfrom the laser-induced material.

The method can create a gap or trench in the laser-induced material. Thegap or trench in the laser-induced material can divide laser-inducedmaterial into a first part and a second part that are not electronicallyconnected to one another with the LIG or LIGS in the laser-inducedmaterial.

The gap or trench can be at least about 40 μm in width.

The gap or trench can be between about 40 μm and about 100 μm in width.

The laser-induced material can be formed by exposing a grapheneprecursor material to a second laser source and conductivity between thefirst part and the second part is around the same as conductivity of thegraphene precursor material.

The first wavelength can be about 1.06 μm.

The laser-induce material can include a LIG material.

The laser-induce material can include a LIGS material.

The laser-induce material can include a composite LIG/LIGS material.

The method can form a 3D object.

The step of selecting a laser-induce material can include selecting alaser-induced material that is entirely coated with LIG, LIGS, or both.The step of exposing the laser-induced material to a first laser sourcecan selectively remove multiple regions of the LIG, LIGS, or both fromthe laser-induced material to form the 3D object.

The step of selecting a laser-induce material can include selecting amaterial that is entirely coated with LIG, LIGS, or both. The step ofexposing the laser-induced material to a first laser source canselectively remove the LIG, LIGS, or both from the laser-inducedmaterial to form the 3D object.

The graphene precursor material can include a polymer.

The polymer can be selected from a group consisting of polymer films,polymer fibers, polymer monoliths, polymer powders, polymer blocks,optically transparent polymers, homopolymers, vinyl polymers,chain-growth polymers, step-growth polymers, condensation polymers,random polymers, ladder polymers, semi-ladder polymers, blockco-polymers, carbonized polymers, aromatic polymers, cyclic polymers,doped polymers, polyimide (PI), polyetherimide (PEI), polyether etherketone (PEEK), polyamide (PA), polybenzoxazole (PBO), polyaramids, andpolymer composites and combinations thereof.

The method can further include a step of incorporating the laser-inducedmaterial into an electronic device, after the step of exposing thelaser-induced material to the first laser source.

In general, in one embodiment, the invention features a laser-inducedmaterial made by a method set forth above.

In general, in one embodiment, the invention features an electronicdevice made by a method set forth above.

In general, in one embodiment, the invention features a methods toproduce an object. The method is a laminated object manufacturingprocess. The object is an LIG, LIGS, or LIG/LIGS object.

In general, in one embodiment, the invention features a method. Themethod includes selecting a first substrate having a first laser-inducematerial disposed on a first side of the first substrate. The firstsubstrate is a first graphene precursor material that can be formed into the first laser-induced material. The first laser-induced material isselected from a group consisting of laser-induced graphene (LIG),laser-induced graphene scrolls (LIGS) materials, and combinationsthereof (LIG/LIGS). The method further includes selecting a secondsubstrate having a first side and a second side. The second substrate isa second graphene precursor material that can be formed in to a secondlaser-induced material. The second laser-induced material is selectedfrom a group consisting of LIG, LIGS, and LIG/LIGS. The method furtherincludes contacting the first laser-induced material on the first sideof the first substrate with the first side of the second substrate. Themethod further includes exposing the second side of the second substrateto a first laser source to form a layer of the second laser-inducedmaterial upon the first laser-induced material.

Implementations of the invention can include one or more of thefollowing features:

Before contacting the first laser-induced material to the first side ofthe second substrate, the method can further include a step ofdepositing a wetting liquid on one or both of (i) the firstlaser-induced material on the first side of the first substrate and (ii)the first side of the second substrate.

The second substrate can have the second laser-induce material disposedon the first side of the second substrate before contacting the firstlaser-induced material to the first side of the second substrate.

The second substrate can have the second laser-induce material disposedon the first side of the second substrate before contacting the firstlaser-induced material to the first side of the second substrate.

The method can be a laminated object manufacturing process.

The step of selecting a first substrate having a first laser-inducematerial disposed on a first side of the first substrate can includeselecting the first substrate and exposing the first substrate to asecond laser source to form the first laser-induce material disposed onthe first side of the first substrate.

The second substrate can be a thin second substrate having a thicknessof at most about 0.005 inches.

The thickness of the second substrate can be at most about 0.001 inches.

The thickness of the second substrate can be at most 3 mm.

The thickness of the second substrate can be at most 1 mm.

The step of selecting a second substrate, contacting, and exposing canbe repeated to form additional layers.

At least ten layers can be formed.

The first graphene precursor material can be a first polymer. The secondgraphene precursor material can be a second polymer. The first polymerand the second polymer can be the same polymer or different polymers.

Each of the first polymer and the second polymer can be selected from agroup consisting of polymer films, polymer fibers, polymer monoliths,polymer powders, polymer blocks, optically transparent polymers,homopolymers, vinyl polymers, chain-growth polymers, step-growthpolymers, condensation polymers, random polymers, ladder polymers,semi-ladder polymers, block co-polymers, carbonized polymers, aromaticpolymers, cyclic polymers, doped polymers, polyimide (PI),polyetherimide (PEI), polyether ether ketone (PEEK), polyamide (PA),polybenzoxazole (PBO), polyaramids, and polymer composites andcombinations thereof.

The wetting solution can include ethylene glycol and water.

The wetting solution can include a solution of water and at least one ofethylene glycol, propylene glycol, and glycerin.

The second laser-induced material can be LIG. The first laser source canhave a duty cycle that is between about 1.5% and about 2%.

The second laser-induced material can be LIGS. The first laser sourcecan have a duty cycle that is between about 10% and about 15%.

The method can further include a step of annealing to remove the wettingliquid.

The step of annealing can be at a temperature of at least 170° C. for 30minutes in air.

One or both of the first substrate and the second substrate can furtherinclude carbon nanotubes.

The method can fabricate a 3D graphene object.

The 3D graphene object can have a thickness of at least 1 mm.

The 3D graphene object can have a mass of at least about 3.5 mg. The 3Dgraphene object can have a porosity of at least about 1.3%.

The 3D graphene object can be capable of having a 20 kPa stress appliedin a first direction without any permanent deformation of the 3Dgraphene object.

The 3D graphene object can maintain the original porous structure of theLIG and LIGS in the 3D graphene object.

One or both of the first substrate and the second substrate can furtherinclude carbon nanotubes.

The carbon nanotubes can be operable to reinforce the 3D grapheneobject.

The 3D object can be selected from the group consisting of mechanicaldampeners, conductive mechanical dampeners, heat conduction blocks,lightweight conductive blocks, templates for growth of biological cells,and composites for bone and neuron growth.

The biological cells can be eukaryote or plant cells.

The method can further include a step of incorporating the 3D grapheneobject into an electronic device.

The electronic device can be selected from a group consisting of supercapacitors, micro-supercapacitors, pseudo capacitors, batteries, microbatteries, lithium-ion batteries, sodium-ion batteries, magnesium-ionbatteries, electrodes, conductive electrodes, sensors, lithium ioncapacitors, photovoltaic devices, electronic circuits, fuel celldevices, thermal management devices, biomedical devices, andcombinations thereof.

The electronic device can be a micro-supercapacitor.

In general, in one embodiment, the invention features a 3D grapheneobject made by a method set forth above.

In general, in another embodiment, the invention features the 3Dgraphene object set forth above.

In general, in another embodiment, the invention features the electronicdevice set forth above.

In general, in another embodiment, the invention features a method thatincludes a first process and a second process. The first process is amethod to make a laser-induced material. The first process includesselecting a first substrate having a first laser-induce materialdisposed on a first side of the first substrate. The first substrate isa first graphene precursor material that can be formed in to the firstlaser-induced material. The first laser-induced material is selectedfrom a group consisting of laser-induced graphene (LIG), laser-inducedgraphene scrolls (LIGS) materials, and combinations thereof (LIG/LIGS).The first process further includes selecting a second substrate having afirst side and a second side. The second substrate is a second grapheneprecursor material that can be formed in to a second laser-inducedmaterial. The second laser-induced material is selected from a groupconsisting of LIG, LIGS, and LIG/LIGS. The first process furtherincludes contacting the first laser-induced material on the first sideof the first substrate with the first side of the second substrate. Thefirst process further includes exposing the second side of the secondsubstrate to a first laser source to form a layer of the secondlaser-induced material upon the first laser-induced material. The secondprocess is a method to remove a first portion of LIG or LIGS from thelaser induced material. The second process includes the step ofselecting the laser-induce material made from the first process. Thelaser induced material is selected from a group consisting of LIGmaterials, LIGS materials, and LIG/LIGS materials. The second processfurther includes exposing the laser-induced material to a second lasersource having a first wavelength to remove a first portion of LIG orLIGS from the laser-induced material.

Implementations of the invention can include one or more of thefollowing features:

The second process can be a method to remove a first portion of LIG orLIGS from the laser induced material set forth above.

The first process can be a method to make a laser-induced material setforth above.

The method further includes a step of incorporating the 3D grapheneobject into an electronic device.

In general, in another embodiment, the invention features a 3D grapheneobject made by the method set forth above.

In general, in one embodiment, the invention features the electronicdevice set forth above.

The foregoing has outlined rather broadly the features and technicaladvantages of the invention in order that the detailed description ofthe invention that follows may be better understood. Additional featuresand advantages of the invention will be described hereinafter that formthe subject of the claims of the invention. It should be appreciated bythose skilled in the art that the conception and the specificembodiments disclosed may be readily utilized as a basis for modifyingor designing other structures for carrying out the same purposes of theinvention. It should also be realized by those skilled in the art thatsuch equivalent constructions do not depart from the spirit and scope ofthe invention as set forth in the appended claims.

It is also to be understood that the invention is not limited in itsapplication to the details of construction and to the arrangements ofthe components set forth in the following description or illustrated inthe drawings. The invention is capable of other embodiments and of beingpracticed and carried out in various ways. Also, it is to be understoodthat the phraseology and terminology employed herein are for the purposeof the description and should not be regarded as limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic of laser in raster mode.

FIG. 1B is a graph showing LIG and LIGS height and mass dependence onlaser fluence.

FIGS. 1C-1H are SEM images of: (FIG. 1C) LIG induced by 117 J/cm² laserfluence made at 1000 PPI image density setting; (FIG. 1D) 500 PPI, 46J/cm² LIGS surface; (FIG. 1E) LIGS of FIG. 1F at higher magnification;(FIG. 1F) 166 J/cm² LIGS with thickness of ˜1 mm made at 500 PPI imagedensity setting; (FIG. 1G) LIG at the interface of LIGS and PI (shown inhigher magnification of FIG. 1F); and (FIG. 1H) “R” shape patternedLIGS. Insets of FIGS. 1C and 1F are schematics for 1000 PPI and 500 PPI,respectively.

FIG. 2A is a Raman spectrum of LIGS showing the D, G and 2D peaks.

FIG. 2B shows the X-ray diffraction with an XRD prominent peak shown at˜26°.

FIG. 2C is an XPS survey spectra of PI (201), LIG (202), and LIGS (203).

FIG. 2D is XPS of C 1s content of PI (204), LIG (205), and LIGS (206).

FIG. 2E is XPS of N 1s content of PI (207), LIG (208), and LIGS (209).

FIG. 2F is XPS of O 1s content of PI (210), LIG (211), and LIGS (212).

FIG. 3A is a TEM images of LIGS.

FIGS. 3B-3D are HRTEM images of LIGS.

FIG. 3E shows a schematic of laser in raster mode with an SEM and HRTEMimages of LIGS.

FIG. 4A is a scheme of LIGS/LIG contact resistance measurement.

FIGS. 4B-4C are, respectively, SEM images of the LIGS forest before andafter the LIGS layer was removed.

FIGS. 5A-5C are SEM images of samples with fluence set at (FIG. 5A) 4.4J/cm², (FIG. 5B) 4.9 J/cm² and (FIG. 5C) 5.5 J/cm². The insets in eachof the SEM images of FIGS. 5A-5C are optical microscope images of thesame spot. The inset optical microscope scale bar is 50 μm.

FIG. 5D is a Raman spectra of the laser spot as fluence was increased(from top to bottom). The laser induction was performed with a 10.6 μm75 W laser in vector mode.

FIG. 6 is a graph showing carbonization fluence with variousirradiation.

FIG. 7A is a schematic of the stress test utilized.

FIGS. 7B-7C are SEM images of the edge of the starting cut. FIG. 7B is aview from the z direction. FIG. 7C is a view from the x direction. (Thegrowth direction of the LIG/LIGS in the starting cut is z).

FIG. 7D-7E are SEM images of the edge of the ending cut. FIG. 7D is aview from the z direction. FIG. 7E is a view from x direction. (Thegrowth direction of LIG/LIGS in the starting cut is x).

FIG. 8 is an SEM image of carbonization with stress.

FIGS. 9A-9H are SEM images of PI samples as the laser fluence wasincreased, with FIGS. 9A-9B at 3.5 J/cm²; FIG. 9C-9D at 4.0 J/cm²; andFIG. 9E-9H at 5.8 J/cm². The laser induction is performed with a 10.6 μm75 W laser in vector mode.

FIGS. 10A-10L are SEM images of PI samples as the laser fluence wasincreased, with FIGS. 10A-10B at 3.5 J/cm²; FIGS. 10C-10D at 4.0 J/cm²;FIGS. 10E-10F at 4.4 J/cm²; FIGS. 10G-10H at 4.6 J/cm²; and FIGS.10I-10L at 5.8 J/cm². Scale bars for FIGS. 10A, 10C, 10E and 10G are 20μm. Scale bars for FIGS. 10B, 10D, 10F, 10H and 10I are 2 μm. Scale barfor FIG. 10K is 1 μm. Scale bare for FIG. 10L is 100 nm.

FIGS. 11A-11C are SEM images of samples with varied fluences (for laserpower 10 W) FIG. 11A at 3.8 J/cm²; FIG. 11B at 4.4 J/cm²; and FIG. 11Cat 5.6 J/cm².

FIG. 12A is an IR transmittance spectrum of PI with ˜52% transmittanceat 9.3 μm and 79% at 10.6 μm.

FIG. 12B-12C are SEM images of single laser pulses with a fluence of 3.2J/cm² with many CNPs being observed.

FIG. 13A is the Raman spectra of the carbon layer resulting fromvariable fluence lases of a 9.3 μm laser with optical image insets.

FIG. 13B is an SEM image of a LIGS forest made with a 9.3 μm laser and25.2 J/cm² fluence.

FIG. 13C is a graph showing LIGS height of both 10.6 μm and 9.3 μm laseswith variable fluences (plots 1301-1302, respectively).

FIGS. 14A-14B are graphs showing average power of each laser that wereused to calculate the fluence.

FIGS. 15A-15D are SEM images of 10.6 μm 75 W laser spot at carbonizationpoint. FIG. 15A is in focus, diameter of 60 μm. FIG. 15B is 0.25 mmoverfocussed, diameter of 65 μm. FIG. 15C is 0.75 mm overfocussed,elliptical axis 75 and 90 μm. FIG. 15D is 1 mm overfocussed (which wastoo inhomogeneous to be reliable). The scale bar for FIGS. 15A-15D is 50μm.

FIGS. 16A-16B are SEM images of 10.6 μm 10 W laser spot at carbonizationpoint. FIG. 16A is in focus. FIG. 16B is 0.25 mm overfocussed. The scalebar for FIGS. 16A-16B is 50 μm.

FIG. 17A is a specific area capacitance comparison ofmicrosupercapacitor made with LIG, LIGS, and LIG-LIGS.

FIG. 17B is an SEM image of the edge of the LIG-LIGS-MSC showed theincorporated ˜50 μm of LIGS.

FIGS. 18A-18D are graphs that reflect sheet resistance with respect tovarious functions, which functions are: for FIG. 18A, laser duty cycleat various laser speeds, laser power 10 W, 500 PPI; for FIG. 18B, laserduty cycle at various PPI, laser power 75 W; for FIG. 18C, fluence at 10or 75 W laser power; and for FIG. 18D, for laser focus (which determinesthe laser spot size).

FIGS. 19A-19B are optical images (reflectance and transmittance,respectively) of LIG with noting the number of times (scans) for itsremoval using a 1.06 μm laser.

FIG. 20 is a graph showing sheet resistance of a LIG material versus thenumber of removing scans of the material.

FIGS. 21A-21B are SEM images of an original sample of LIG at the surfaceand cross-section, respectively.

FIGS. 21C-21D are SEM images of the sample of LIG at the surface and across-section, respectively, after one removal scan.

FIGS. 21E-21F are SEM images of the sample of LIG at the surface and across-section, respectively, after two removal scans.

FIGS. 21G-21H are SEM images of the sample of LIG at the surface and across-section, respectively, after five removal scans.

FIGS. 21I-21J are SEM images of the sample of LIG at the surface and across-section, respectively, after ten removal scans.

FIG. 22 is a graph showing sheet resistance of a LIG material having a 1cm gap created by line pattern and 100 μm width pattern.

FIGS. 23A-23B are SEM images of a LIG material having, respectively, aline pattern and 100 μm width pattern after ten removal scans.

FIGS. 24A-24F are SEM images of “R” letters from LIG on a PI substrategenerated by three different approaches. FIGS. 24A-24B are SEM imagesresulting from the first approach.

FIGS. 24C-24D are SEM images resulting from the second approach. FIGS.24E-24F are SEM images resulting from the third approach.

FIG. 25A is schematic of a 3D printing process of embodiments of thepresent invention.

FIGS. 25B-25C are SEM images of the 3D printed LIG and 3D printed LIGS,respectively.

FIG. 25D is a graph showing the thickness of printed LIG/LIGS withvarious PI layers.

FIGS. 25E-25F are TEM images of 3D printed LIG and 3D printed LIGS,respectively.

FIG. 25G are Raman spectra of various 3D printed LIG/LIGS.

FIGS. 25H-25I are HRTEM images of 3D printed LIG. And 3D printed LIGS.

FIG. 25J is a thermal gravimetric analysis (TGA) of 3D LIG.

FIGS. 26A-26B are different perspective views of a schematic of anautomated LOM process to make 3D LIG or LIGS.

FIG. 26C is an image of an automated LOM process to make 3D LIG or LIGS.

FIGS. 27A-27E are SEM images of cross-sections of 3D printed LIG with,respectively, 1-5 3 D printed layers.

FIG. 27F is a graph showing the thickness of the 3D printed LIG versusthe number of 3D printed layers.

FIG. 28A-28B are SEM images of 3D printed LIG.

FIGS. 29A-29E are SEM images of cross-sections of 3D printed LIGS with,respectively, 1-5 3D printed layers.

FIG. 29F is a graph showing the thickness of the 3D printed LIGS versusthe number of 3D printed layers

FIG. 30A-30B are SEM images of 3D printed LIG.

FIGS. 31A-31E are optical images taken during a stress test for a 5×5×5mm LIGS cube made by 3D printing.

FIG. 31F is a stress-strain test for a LIG/PDMS composite.

FIG. 32A is a schematic for the milling with fiber laser used to millLIG made by 3D printing process.

FIG. 32B is an SEM image of a cross-section of the LIG with multiplemilling.

FIG. 32C is a Raman spectra of the LIG with multiple milling.

FIG. 32D is an SEM image after complete removal of the LIG with singleline of fiber laser (resolution is observed with 20 μm).

FIG. 32E is an SEM image of an “R” letter made from 3D LIG with fiberlaser tailoring.

FIG. 33 is an optical image of an “R” letter of LIG made by 3D printing.

FIGS. 34A-34B are, respectively, a schematic and image of a surfaceconductivity measurement utilizing LIG made by 3D printing process.

FIG. 34C is an I-V curve for 3D printed LIG with various PI layerthickness.

FIGS. 35A-35B are graphs showing cycle performance of a lithium ionsupercapacitor half-cell utilizing LIG made by 3D printing process. FIG.35 A is for the anode (337.61 mAh/g).

FIG. 35B is for the cathode (60.66 mAh/g).

FIG. 36A is an image of stress-strain testing apparatus for the PDMS/LIGcomposite. The inset is an image of the LIG/PDMS composite (dog-boneshape sample).

FIG. 36B is a graph comparing the elongation property of the PDMS/LIGcomposite and PDMS.

DETAILED DESCRIPTION Laser-Induced Graphene Scrolls (“LIGS”)

The present invention to LIGS and the method of making LIGS. In someembodiments, LIGS are fabricated by exposing a precursor material (e.g.,a polymer, such as a polyimide) to a laser source to form the LIGS fromthe precursor material. In some embodiments, the LIGS of the presentdisclosure are fabricated by the adjusting methods for the fabricationof LIG from commercial polyimide films [Lin 2014]. Such methods tofabricate LIG were disclosed and taught in the Tour '351 PCT applicationand the Tour '060 PCT application.

Various laser parameters may be used. By tuning the laser parameters(operational modes, PPI, duty cycle) LIGS have been produced. The fluiddynamics process of the carbon-forming event can be captured in thesolidified material. Such better understanding of the laser parametersprovided control over the carbon morphology, thus enabling thefabrication of millimeter-scale vertical aligned LIGS forests. Thedetails of the graphene scrolling structure of LIGS have been examined.The application of LIGS in micro-supercapacitor (MSC) results in twotimes capacitance of LIG-LIGS-MSC over LIG-MSC, reflecting the potentialof LIGS in flexible electronic device configurations.

For instance, in some embodiments, the laser source has a laser fluenceof more than about 40 J/cm². In some embodiments, the laser source has alaser fluence ranging from about 40 J/cm² to about 200 J/cm². In someembodiments, the laser source has a laser fluence ranging from about 80J/cm² to about 170 J/cm².

Such methods may be utilized to fabricate various LIGS. For instance, insome embodiments, the LIGS are generated from the LIG disclosed andtaught in the Tour '351 PCT application and the Tour '060 PCTapplication. In other embodiments, the LIGS include graphenes thatscroll up to form fibers with small diameters (e.g., diameters of atmost around 100 nm). In some embodiments, the LIGS have diametersranging from about 10 nm to about 500 nm. In embodiments, the LIGS ofthe present disclosure have diameters ranging from about 20 nm to about100 nm.

In some embodiments, the LIGS of the present disclosure grow in bundlesto form forests with long heights (e.g., heights of up to 1 mm, asopposed to the 20 micron thicknesses of prior LIG). In some embodiments,the LIGS of the present disclosure have thicknesses of more than about20 μm, more than about 30 μm, more than about 100 μm, more than about500 μm, and more than about 1 mm.

LIGS can be made by lowering the consecutive laser pulse stackingdensity. LIGS can be formed by a one-step laser thermolysis process at aradiation energy >40 J/cm². By applying a commercial laser CO₂ rastermode, the vertical growth of a forest of LIGS with a height of 1 mm wasafforded in one step. The effect of a 9.3 μm wavelength laser wascompared to the previously used 10.6 μm wavelength laser and parametershave been discovered to reliably control the LIG versus LIGSmorphologies for device optimization. Interdigitatedmicrosupercapacitors (MSCs) from LIGS and LIGS-LIG hybrids have alsobeen fabricated. MSC devices fabricated from LIGS and LIGS-LIG hybridsshow two times the specific areal capacitance of MSC made entirely fromLIG, showing that LIGS can be utilized in flexible device applications.

Commercial laser cutting systems have two modes, vector and raster. Invector mode, the laser follows a pattern in both the x and y direction.As shown in the schematic of FIG. 1A, in the raster mode, the laserscans the 2D pattern in the x-direction only. The laser inductionprocess was changed from vector mode to raster mode in order to preparea large area of LIG material. Fluence is measured as accumulated energyover a unit area. Similar to other commercial laser systems, the imagedensity is controlled by the following two factors: the pulse widthmodulation or pulses per inches (PPI), and the lines per inch (LPI),both an indication of the density of the laser lines. As in the previousreports of the inventors, lasering for LIG was done at 1000 PPI×1000 LPI(pulse separation 25.4 μm) with a laser spot size of ˜100 μm, resultingin a LIG thickness of 30 μm [Lin 2014]. In that case, the laser spotsinduced on the PI surface overlapped, leading to overheating anddestruction of the top LIG layers, thus resulting in the remaining LIGlayers having thickness <50 μm regardless of the fluence. See FIG. 1B(showing (a) LIG height and mass dependence on laser fluence by plots101 and 102, respectively, and (b) LIG height and mass dependence onlaser fluence by plots 103 and 104, respectively) and FIG. 1C.

In order to preserve the LIG layers, which turned out to be LIGS, animage density of 500 PPI×500 LPI (pulse separation 50.8 μm) with a laserspot size of ˜60 μm was used to ensure that each pulse waswell-separated from its neighboring pulse. See FIG. 1D. The resultingheight-controllable and tubular nanostructure LIGS has a verticallyaligned forest morphology. The laser system provides a lateralresolution of 2 μm that provides high resolution spacing between eachcolumn and row. As shown in FIGS. 1E-1G, using a laser pulse withfluence of 166 J/cm², a LIGS forest with ˜1 mm height was synthesizedbefore the 120-μm-thick PI substrate was entirely converted to LIGS.FIG. 1E is an SEM image of the LIGS in higher magnification from area105 of FIG. 1F. FIG. 1G is an SEM image of the LIGS in highermagnification from area 106 of FIG. 1F (at the interface of LIGS andPI).

It should be noted that the laser treatment process was relatively fast:1 min for a 1 cm² pattern even at low raster speed. A thin LIG layer of˜30 μm was also found at the interfaces between the LIGS and PI. SeeFIG. 1G. As discussed below, a conductivity test showed seamlesselectrical conductance between the interfacial LIG and LIGS forest.

It has been found that the LIGS forest can be patterned with aresolution of the laser spot size (˜60 μm). The optical system can beimproved for higher resolution but the limitation of the patternresolution is the diffraction limit (˜5 μm, half of the 10.6 μmwavelength). As shown in FIG. 111, an “R” shape patterned LIGS was madeto demonstrate the laser system resolution capability.

Accordingly, various methods may be utilized to fabricate LIGS. In someembodiments (e.g., embodiments where synthesis of large areas of LIGSare desired), a laser that operates in raster mode can be utilized. Insome embodiments, image density is changed by pulses per inch (PPI) andlines per inch (LPI, the density of laser lines).

In some embodiments, the LIGS can be fabricated by making each pulsewell-separated (e.g., pulse separation of 50.8 μm with a laser spot sizeof 50 μm), thereby resulting in height controllable tubulenanostructures that are vertically aligned in a forest. In someembodiments, the LIGS can be fabricated by utilizing an image density of500 PPI×500 LPI with a pulse separation of 50.8 μm and a laser spot sizeof 50 In some embodiments, the LIGS can be fabricated by utilizing animage density that is less than 1000 PPI×1000 LPI. In some embodiments,the LIGS can be fabricated by utilizing a pulse separation of more than25.4 μm. In some embodiments, the LIGS can be fabricated by utilizing alaser spot size of less than ˜100 μm.

As illustrated in FIG. 1F, using laser pulses with a fluence of 80J/cm², LIGS forest have been created with heights up to 1 mm before the120-μm PI substrate could be carbonized to amorphous carbon. The LIGSgrow in bundles created by each laser pulse.

As shown in FIG. 1G, a thin LIG layer of about 30 μm can be prepared andinterfaced between LIGS and the PI.

Laser spots overlapping resulted in LIG layers with thicknesses under 50μm, regardless of the fluence. It is believe that, in that circumstance,the laser has vaporized the LIGS product from the prior pulse. The LIGSforest can be patterned with resolutions of approximately the laser spotsize (˜75 μm). Optical systems can be improved for higher resolution.However, the initial limitation of the pattern resolution can be thediffraction limit (˜5 half of the 10.6 μm wavelength). In someembodiments, advanced optical schemes developed for use in thelithography industry can be used for improved performance.

For example, for the formation of LIGS, the pulse density should beperformed so that each of the pulses do not overlap. As compared to 1000PPI in the laser utilized, the 500 PPI was better at focusing in term ofthe pulse density to generate LIGS. Furthermore, a certain amount offluence (energy density) was needed to initiate the formation of LIGS.For 10.6 μm and 9.3 μm laser they are ˜40 J/cm² and ˜20 J/cm²,respectively (in laser system parameter, that was 500 PPI, raster speedof 6 in/s, duty cycle of 2% and 1% respectively). Still further,depending on the laser, there is a maximum height of LIGS that can begenerated because excessive laser radiation will ablate the previousformed LIGS and decrease the final height of the forest.

LIGS Elemental Composition

To confirm the graphitic nature and elemental composition of theobtained LIGS, Raman spectra, X-ray diffraction (XRD) and X-rayphotoelectron spectroscopy (XPS) spectra of LIGS were obtained for asample made with a fluence of 122 J/cm². In FIG. 2A, Raman spectra showa strong D peak at ˜1350 cm⁻¹ induced by defects or symmetry brokensites [Ferrari 2007]. A sharp 2D peak at ˜2700 cm⁻¹ with ˜1.25I_(G)/I_(2D) ratio indicates a few-layer graphene structure [Sun 2012].

In the XRD shown in FIG. 2B, a prominent peak is observed at ˜26°,representing the (002) graphitic crystal planes. This gives aninterlayer spacing of ˜3.4 Å, well-matched with the graphitic phase. A(100) graphitic crystal phase is also shown at an angle of ˜43°.

FIG. 2C is an XPS survey spectra of PI (201), LIG (202), and LIGS (203).FIG. 2D is XPS of C 1s content of PI (204), LIG (205), and LIGS (206).FIG. 2E is XPS of N 1s content of PI (207), LIG (208), and LIGS (209).FIG. 2F is XPS of O 1s content of PI (210), LIG (211), and LIGS (212).These show that the content of oxygen in LIGS is 3% withoutXPS-detectible nitrogen content. This is lower than the LIG made with afluence of 29 J/cm², which has 1.1% nitrogen and 4.2% oxygen.

LIGS Structure

To further investigate the structure of LIGS, a LIGS/CHCl₃ suspensionwas dropped onto a lacey carbon grid for transmission electronmicroscopy (TEM) characterization. FIG. 3A represents a typical TEMimage and shows 50-100 nm diameter LIGS emanating from LIG. LIGS areentangled together, but the alignment is roughly preserved even aftersolution bath sonication.

From high-resolution TEM (HRTEM) images in FIGS. 3B-3C, LIGS showed afew-layer graphene structure with disordered fringes found on the focalplane and ordered fringes near the edge of LIGS. FIG. 3B is a typicalLIGS ordered fringes. FIG. 3C shows LIGS with size of 40-50 nm alsoobserved with ordered fringes on the edges with distances of 3.4 Å. Thehighly disordered structure observed in the HRTEM agrees well with thehigh I_(D)/I_(G) ratio seen in the Raman spectra. The concentration ofordered fringes at the edges suggest graphitic curves at the edges ofthe LIGS, resulting from the scrolling of LIG to form LIGS. The pointthat LIG tears and scrolls into LIGS is indicated by arrow 301 in FIG.3A. This can also be seen in the SEM image of FIG. 3D (where LIG scrollsinto LIGS. The scrolling of LIGS can also be seen in FIG. 3D that showsthe tip of a LIGS with its hollow structure (a tip of a single LIGS withan open end).

FIG. 3E shows a schematic 302 of laser in raster mode that has made LIGSon PI 303. (Schematic 302 is similar to the schematic as shown in FIG.1A and described above). Image 305 is an SEM image of LIGS, such as LIGSformed in area 304 shown in schematic 302. Image 307 is an HRTEM imageof box 306 in SEM image 305. (HRTEM image 307 is the same HRTEM image asshown in FIG. 3C and as described above).

Conductivity

Conductivity tests were performed to measure the electrical conductancebetween the interfacial LIG and LIGS forest. FIG. 4A is a scheme ofLIGS/LIG contact resistance measurement. First, 1×1, 1×2, 2×2 and 2×3cm² LIGS forests (having PI 403, LIG 402, and LIGS 404) were made inconjunction with 1×2 or 2×4 cm² LIG (having PI 403 and LIG 402), thensilver paint 403 was applied on top of the LIGS forest area and 1×1 and2×2 cm² of LIG to measure the resistivity. The LIGS layer then wasremoved to reveal the LIG beneath and silver paint was applied again tomeasure the resistivity.

FIG. 4B shows there is no pathway between the top silver paint 403 layerand the LIG 402 layer (which is beneath the LIGS 404 layer) that wouldlead to an electrical short. FIG. 4C shows that the silver paint 403layer to the LIG 402 layer after the LIGS layer was removed.

Resistance was measured between 2 silver paste electrodes before andafter removing the LIGS, which measurements are reflected in TABLE 1,below. These measurements show little to no contact resistance betweenLIG and LIGS.

TABLE 1 LIGS forest area (cm²) Material 1 × 1 1 × 2 2 × 2 2 × 3Ag/LIG/LIGS/Ag (Ω) 502 398 135 102 Ag/LIG/Ag (Ω) 499 397 135 102

This shows showed seamless electrical conductance between theinterfacial LIG and LIGS forest.

Carbonization

Applicant has discovered parameters for the controlled formation ofvarying LIG morphologies. When changing the total radiation energy perunit area on LIG, it was found that a critical fluence point of ˜5 J/cm²and ˜2.1 J/cm² was needed to initiate the carbonization process in PIusing a 10.6 μm and 9.3 μm laser, respectively. This decrease in thecritical fluence point of 2.3 times agreed well the decrease inabsorption of the PI at 10.6 μm infrared and 9.3 μm laser infrared,which is also 2.3 times. When increasing the radiation energy, thephysical formation of LIG follows a fluid dynamics process in that themorphology of the LIG progressively changes from sheets to filaments andfinally to droplets.

Raman spectroscopy was used as a tool to determine when carbonizationbegan, with confirmation from optical microscopy. A commercial UniversalLaser System XLS10MWH laser cutter platform was used as the laser sourceoperated in pulse width modulation (PWM) and equipped with two 10.6 μmwavelength lasers at 75 W and 10 W and one 50 W 9.3 μm wavelength laser.In a previous report from the inventors [Lin 2014], a porous LIGstructure with a few-layer graphene structure can be generated duringlaser induction under ambient conditions at room temperature when a CO₂laser (10.6 μm) is focused on the surface of polyimide (PI) sheets witha laser power of 60 Win 4% to 10% duty cycles at a frequency of 6 kHzand 1000 pulses per inch (PPI). Under such conditions, the thickness ofthe LIG on the surface of PI sheets was <50 μm regardless of the dutycycle.

The interaction of individual laser pulses upon PI from the 10.6 μm 75 Wlaser was determined. To single out each pulse, the laser pattern wasset in vector mode (in which the laser moves in a line pattern) withpulse separation from 30 to 400 PPI. The laser radiation energy density,or fluence, was measured by averaging many pulses. The laser parametersutilized are discussed below.

Raman spectroscopy was used as a tool to determine when carbonizationbegan, with confirmation from optical microscopy. In FIG. 5D, Ramanspectra at a low fluence of ˜4.4 J/cm² had an appearance similar to thatof bulk PI, indicating that little or no carbonization occurred, whichwas consistent with the lack of black carbon noted in the optical imageof the inset of FIG. 5A.

When the laser fluence was increased to ˜4.9 J/cm², D and G peaks at˜1350 cm⁻¹ and ˜1590 cm⁻¹ were visible in the Raman spectrum, indicatingthat carbonization had begun. The optical image of the inset of FIG. 5Bconfirmed carbonization with the appearance of a black spot. Note thatthe surface of the PI sheet is kept scratch-free during theseevaluations because surface roughness can cause a fluence reduction atthe carbonization point.

When the laser fluence was further increased to ˜5.5 J/cm², theappearance of the 2D peak at ˜2700 cm⁻¹, resulting from second orderzone boundary phonons [Ferrari 2006], indicated more completegraphitization of PI and formation of graphene as confirmed in FIG. 5C.

Laser irradiation (W/m²) and pulse duration are not used ascarbonization units because the laser pulse profile is not continuousbut an exponential rise followed by exponential decay. Therefore,fluence is the better choice for determining the carbonization unit. Asconfirmation of this, the 75 W laser was defocused and the 10 W laserwas used to vary the irradiation. With irradiation ranging from 22 to265 GW/m², the same fluence of ˜5 J/cm² was necessary for carbonization.See FIG. 6, which shows carbonization fluence with various irradiationwith line 601 at 4.9 J/cm². This fluence range is well within the rangefor commercial CO₂ laser systems where the laser power is 10 to 100 Wand the laser spot size is 50 to 100 μm. At this range, the heat loss bythermal conduction was found to be negligible in the process.

Examination of the fine structure generated at different fluence pointsrevealed what is believed to be the dynamics of the carbonizationprocess. PI is known for its oxygen and nitrogen outgassing at 550° C.,followed by carbonization at 700° C. and finally graphitization at 3000°C. [Inagaki 1991; Inagaki 1989]. As a result of rapid outgassing fromthe PI melt, it undergoes fluid fragmentation. Evidence of PI liquefyingduring the laser-induced process is shown in the stress test in FIGS.7A-7E and FIG. 8.

FIG. 7A is a schematic of the stress test in which a strip of PI 701 wasstressed in the x direction (shown by arrows 702-703) and the strip 701was cut by the laser in the y direction (shown by arrow 704). The stresstest was done to establish that the PI liquefied during its conversionto LIG. As shown in FIGS. 7B-7C (SEM images of the edge of the startingcut at views z and x, respectively), at the starting point of the cut,the LIG morphology is in the z direction where there is no stress. Asshown in FIGS. 7D-7E (SEM images of the edge of the ending cut at viewsz and x, respectively), at the end of the cut where the stress field wasstrong, the LIG morphology is in the x direction, parallel to the stressfield.

FIG. 8 is an SEM image of carbonization with stress. As shown in FIG. 8,the stress is horizontal in this figure. The morphology of the LIG/LIGSis toward the stress field. The transition is from bulk PI on the rightto deformed PI in the middle then to carbonized material on the left.

Previous studies showed the fluid dynamics of such breakup results in acascade of sheets, ligaments and droplets [Scharfinan 2016]. As shown inFIGS. 9A-9H and FIGS. 10A-10H, similar dynamics were observed in thelaser induction process that can be divided into the following fourstages:

(1) At low fluence (3.5 J/cm²) as shown in FIGS. 9A-9B and 10A-10B, thecarbonization is limited due to low energy input and a majority of theformed nanostructures are thin sheets of PI. FIG. 9B is a magnificationof area 901 of FIG. 9A. FIG. 10B is a magnification of area 1001 of FIG.10A.

(2) At higher fluence (4.0 J/cm²), as shown in FIGS. 9C-9D and FIGS.10C-10H, the sheet nanostructure starts to break into filaments.Examples of transition from sheets to filaments is indicated with arrow903 in FIG. 9D, arrow 1003 in FIG. 10D, and arrow 1006 in FIG. 10H. FIG.9D is a magnification of area 902 of FIG. 9C. FIG. 10D is amagnification of area 1002 of FIG. 10C. FIG. 10F is a magnification ofarea 1004 of FIG. 10E. FIG. 1011 is a magnification of area 1005 of FIG.10G.

(3) At a fluence point high enough for carbonization (5.8 J/cm²), asshown in FIGS. 9E-9H and FIGS. 10I-10L, sheet and filament featuresremain but in graphitic form as indicated by strong D and 2D peaks inthe Raman spectra. See FIG. 5D. FIGS. 9E and 9G are, respectively,magnifications of areas 904 and 905 of FIG. 9F. FIGS. 10I and 10K are,respectively, magnifications of areas 1007 and 1008 of FIG. 10J.

(4) At this high fluence point, the transition from filament tocarbonized droplets can be observed as shown in FIGS. 9G-9H and FIGS.10I-10L. Based on the Raman spectral analysis of the samples of FIGS.10A-10L, only the sample in FIGS. 10I-10L with laser fluence of 5.8J/cm² is carbonized.

These carbonized droplets can form carbon nanoparticles (CNPs) that aremostly blown away by the laser air assist. In comparison, for samples atthe same fluences but with the 10 W 10.6 μm laser, similar fluence forcarbonization was observed, but the morphology is slightly favored thesheet-like structures. See FIGS. 11A-11C. When compared to the 75 Wlaser, the 10 W laser utilized for the samples in FIGS. 11A-11C inducesthe same carbonization area and has the same critical carbonizationpoint but favors more LIG structure, as can be seen in the 5.6 J/cm²sample of FIG. 11C.

In prior reports by the inventors [Lin 2014], the inventors suggestedthat the carbonization process was induced by a photothermal process.Therefore, higher laser absorption would result in better carbonization.By Fourier transform infrared spectroscopy (FTIR), the absorption of PIat 9.3 μm is ˜2.3× larger than at 10.6 μm. See FIG. 12A.

In FIG. 13A, the 9.3 μm laser was used for the laser induction on PIsheets, and the Raman and optical microscopy results revealed that thecritical carbonization point was ˜2.1 J/cm², which is ˜2.3× less thanthe value 4.9 J/cm² when using the 10.6 μm laser. Even though theabsorption and critical point of carbonization agree well with eachother (the absorption of PI at the 9.3 μm wavelength infrared is 2.3×larger than that of the 10.6 μm wavelength infrared), one cannotcompletely attribute the fluence at carbonization only to theabsorption; other factors, such as heat conductivity or changes of IRabsorption at higher temperatures, could also play a rule. Nonetheless,there is a correlation. The morphology differences can be seen in FIGS.12B-12C such that at high fluence, LIGS and CNPs are favorednanostructures because with higher absorption at 9.3 μm, only thinlayers of PI receive the laser energy, possible resulting in more abruptliquid dynamics than obtained with the 10.6 μm laser. Interestingly, asthe fluence increases, the thickness of the LIGS decreases. It isbelieve this is because of the higher production of CNPs or vaporizationof the PI. If only hundreds of microns of LIGS are needed, use of astrong absorption laser can be possible. Otherwise, if the applicationneeds LIGS at thicknesses of about 1 mm, weak absorption lasers such asthe 10.6 μm CO₂ laser afford these thick LIGS forests.

Laser Parameters

The commercial Universal Laser Systems instrument had three adjustableparameters: (a) speed, the percentage of maximum speed that is 120inches/s in raster mode and 40 inches/s in vector mode; (b) power, theduty cycle of the pulse width modulation (PWM); and (c) PPI, which isthe density of the laser pulses. A Sciencetech 365 Power and EnergyMeter was used to measure the fluence in the two modes, vector andraster mode.

Vector mode. The vector mode was used to measure individual fluence ofeach laser pulse. The speed was set at 1% (0.4 inches/s). The duty cyclewas set up at 0.1% for both the 75 W 10.6 μm and 50 W 9.3 μm laser and1% for 10 W the 10.6 μm laser. The fluence was changed by changing thePPI. The laser fire within an infinite circle pattern around the energymeter disk and average power is measured after reaching equilibrium at˜1 min. FIG. 14A shows the various PPI in vector mode with laserparameter: 1% speed, 0.1% duty cycle for 10.6 μm 75 W laser (plot 1401),0.1% duty cycle for 9.3 μm 50 W laser (plot 1402), and 1% duty cycle for10.6 μm 10 W laser (plot 1403).

Fluence of the laser was then calculated using Eq 1:

$\begin{matrix}{H = {\frac{1}{{PPI} \times 0.4}\frac{P_{V}}{S}}} & ( {{Eq}\mspace{14mu} 1} )\end{matrix}$

where the first term is the duration time for each cycle with P_(v)being the average power of the laser taken from FIG. 14A. S is the areaof the round laser spot taken from SEM image (FIGS. 15A-15D and16A-16B).

Raster mode. The raster mode was used to measure the fluence of LIGSforest. The laser runs a pattern of 1 cm² square with fixed speed at 5%(6 inches/s), 500 PPI for LIGS and 1000 PPI for LIG. Average power P_(R)is read at the end of the pattern in FIG. 14B, after ˜1 min. FIG. 8Bshows the raster mode with various duty cycle and fixed 5% speed, with75 W 1000 ((plot 1404), 75 W 500 PPI (plot 1405), and 50 W 500 PPI (plot1406).

Accumulated fluence (J/cm²) of each laser spot is then calculated usingEq 2:

H=t×P _(R)  (eq 2)

where t is the time for the laser to complete the square pattern (60 secfor 500 PPI and 117 sec for 1000 PPI).

LIGS Applications

The LIGS of the present invention can be utilized in a variety ofutilities. Due to the high surface areas disorders within LIGS,Applicants expect improvements in such LIG applications. With higheryield and surface area, LIGS could serve as enhanced materials fornumerous applications. Moreover, the fabrication of LIGS can beperformed in ambient air with existing commercial laser systems andprecursor materials (e.g., polyimides). Therefore, the fabricationmethods are effective in terms of time and costs.

For instance, the LIGS can be utilized as components of energy storagedevices, such as microsupercapacitors MSCs with in-plane interdigitatedshape. The capacitance of the first generation of LIG-MSCs reaches to 4mF/cm² [Lin 2014], comparable to other carbon based MSCs. Follow-upstudies increased it to 16 mF/cm² by the use of solid-state electrolyteand boron doping [Peng 2015 B]. Additional research introducedpseudocapacitive materials into LIG devices by electrochemicaldeposition, and the capacitance value further increased to 950 mF/cm²[Li 2016].

The LIGS can also be utilized in the field of oxygen reduction reactioncatalysts by in situ formation of metal oxide nanoparticles (aspreviously used on LIG [Ye 2015]).

Representative of an application of LIGS, in-plane interdigitated solidstate MSC was fabricated from LIGS and compared it to MSCs fabricatedfrom LIG alone. The interdigitated device size with neighboringelectrode distances of 300 μm was kept the same as previously report[Lin 2014]. FIG. 17B is an SEM image of the edge of LIG-LIGS-MSC showedthe incorporated ˜50 μm of LIGS (with arrows pointing to LIG 1704 andLIGS 1705).

To fabrication the flexible all-solid-state MSCs, PVA/H₂SO₄ was used asthe solid electrolyte for all of the devices. It was made by stirring 10mL of DI water, 1.0 mL of sulfuric acid (98%, Sigma-Aldrich), and 1.0 gof PVA at 80° C. overnight. Approximately 0.25 mL of the electrolyte wasapplied to the active area of the devices, and was dried under ambientconditions for 4 h. The all-solid-state MSCs were obtained after dryingin a vacuum desiccator (˜120 mm Hg) overnight for further solidificationof the electrolyte.

The electrochemical performances of the flexible all-solid-state MSCswere characterized by CV, galvanostatic charge-discharge experiments,and EIS using an electrochemical station (CHI 660D). The areal specificcapacitance (C_(A)) and volumetric specific capacitance (C_(V)) ofelectrode materials were calculated from galvanostatic charge-dischargecurves according to eq 3 and eq 4, respectively:

C _(A)=4I/(A _(Device)×(dV/dt))  (eq 3)

C _(V)=4/I(V _(Device)×(dV/dt))  (eq 4)

where I is the current applied, A_(Device) is the total area of thedevice, V_(Device) is the total volume of the device, and dV/dt is theslope of the discharge curve.

The areal capacitance (C_(Device, A)) and volumetric capacitance(C_(Device, v)) of the MSCs were calculated by using eqs 5 and 6,respectively:

C _(Device, A) =C _(A)/4  (eq 5)

C _(Device, V) =C _(V)/4  (eq 6)

FIG. 17A is a specific area capacitance comparison ofmicrosupercapacitor made with LIG (plot 1701), LIGS (plot 1702), andLIG-LIGS (plot 1703). As seen in FIG. 17A, the fabricated LIGS-MSC has aspecific area capacitance higher than LIG-MSC by 50%.

One of the key elements of the MSC is the low sheet resistance. I.e.,sheet resistivity is a key characteristic that indicates how the LIGSwill perform in a device.

FIGS. 18A-18D are graphs that reflect sheet resistance with respect tovarious functions. For FIG. 18A, this shows sheet resistance as afunction of laser duty cycle at various laser speeds (2%, 3% 4%, 5% 10%and 20% for plots 1801-1806, respectively), laser power 10 W, 500 PPI.For FIG. 18B, this shows sheet resistance as a function of laser dutycycle at various PPI, laser power 75 W (500 PPI at 2% and 5% speed forplots 1807-1808, respectively, and 1000 PPI at 2% and 5% speed for plots1809-1810, respectively). For FIG. 18C, this shows sheet resistance as afunction of fluence at 10 or 75 W laser power (plots 1811-1812,respectively). For FIG. 18D, this shows sheet resistance as a functionof laser focus (which determines the laser spot size) (plot 1803).

As shown in FIG. 18A, the LIGS sheet resistance is 100 to 200 Ω/sq, fivetimes that reported for LIG at 20 Ω/sq. LIG that is fabricated with 1000PPI (FIG. 1C inset) has more overlapping of laser pulses than the LIGSthat is fabricated with 500 PPI (FIG. 1F inset). Thus, LIG is made withmore electrical conductive pathways, resulting in lower sheet resistancewhen compared with LIGS. Therefore, to incorporate LIGS into LIG-MSC,the LIG-MSC was supplemented with a line of 50 μm LIGS. The specificarea capacitance increased 2 times when compared to that from LIG.Hence, a small amount of LIGS introduced a large amount of chargestorage capacity into the MSC.

Additional variations to the LIGS can be as follows:

For instance, the starting polymer to make the LIGS can be selected froma group consisting of polymer films, polymer fibers, polymer monoliths,polymer powders, polymer blocks, optically transparent polymers,homopolymers, vinyl polymers, chain-growth polymers, step-growthpolymers, condensation polymers, random polymers, ladder polymers,semi-ladder polymers, block co-polymers, carbonized polymers, aromaticpolymers, cyclic polymers, doped polymers, polyimide (PI),polyetherimide (PEI), polyether ether ketone (PEEK), polyamide (PA),polybenzoxazole (PBO), polyaramids, and polymer composites andcombinations thereof. For instance, the polyamide (PA) can be Kevlar(and thus can encompass uses for the resulting LIGS materials ofprotection, armor, cryogenics, etc.)

The LIGS can be doped with one or more dopants. The dopants can include,without limitation, heteroatoms, metals (e.g., metal salts), andcombinations thereof. The dopant can be boron. The dopant can be a metalnanoparticle that forms as metal nanoparticle-doped structure.

Different kinds of environments may be used in the fabrication of LIGS.For instance, different laser conditions may be utilized in thefabrication of LIGS.

LIGS can have lower surface resistance than LIG due to laser pulses thatdo not overlap effectively. Larger laser spot sizes with the sameradiation density may be utilized with more overlapping between eachpulses in order to enhance surface resistance.

LIGS can be combined with LIG.

Various gases may be introduced into the LIGS fabrication environment.

Laser-Induced Removal of LIG and LIGS

Embodiments of the present invention further include a laser-inducedremoval process to remove LIG from a LIG material (or LIGS from a LIGSmaterial). While the discussion below focuses primarily on laser-inducedremoval of LIG, the present invention also applies to LIGS.

PI films can be converted into LIG by treatment with a 10.6 μm CO₂laser. The minimum line width that could be fabricated was ˜100 μm. Alaser-induced removal process has been discovered to etch away the LIG,such as using a 1.06 μm fiber laser. This provides the ability to make10 times finer patterns, and to use it as an etching process, to eitherselectively thin the LIG or to etch it all the way down to the base PIlayer. In this manner, 3D control can be obtained in patterning of theLIG thickness and resistivity. This permits far great dynamic control ofthe LIG process. This also permits the more controlled patterning of LIGdesigns in electronics and water purification platforms devices.

The laser-induced removal process can include that the wavelengths ofthe lasers for the two laser-induction steps are not the same, i.e., thewavelength of the laser used to create the LIG is different than thewavelength of the laser used to perform the laser-induced removal of theLIG.

The laser-induced removal process can also and/or alternatively includethat the laser-induced removal step is performed in predeterminedpatterns.

The laser-induced removal process can also and/or alternatively includethat the laser-induced removal step is repeated over the same area ofthe LIG to result in deepening of successive laser-induced removaldepths.

For instance, in embodiments of the present invention, a laser system(Universal laser system XLS10MWH) was utilized with the substrate beingcommercial Kapton polyimide sheet, 0.005″ thickness. The conditions tomake the LIG sheet (to be used for removal) were 75 W 10.6 μm laseroperating at 6 kHz and 2% duty cycle with 1000 pulses/inch image densityand patterning speed of 6 inches/s. The initial LIG sheet resistance: 40Ω/sq., thickness: 40 μm. The fiber laser conditions (for the removalscans) were a 50 W 1.06 μm laser operating at 30 kHz and varying dutycycle with 1000 pulses/inch image density and patterning speed of 6inches/sec.

FIGS. 19A-19B are optical images (reflectance and transmittance,respectively) of the LIG sheet. These figures note the number of times(scans) for such removal using the 1.06 μm laser, which number of scans1901-1905 are original (0), 1, 2, 5, and 10 scans, respectively. Asshown in FIGS. 19A-19B, the fiber laser removed LIG with each successivescan. After ten scans, the bare polyimide appears with small lighttransmittance, the LIG becoming discrete.

FIG. 20 is a graph showing plot 2001 of sheet resistance of a LIGmaterial versus the number of removing scans of the material. As shownin FIG. 20, under 5 times of removal, the LIG still maintained goodsheet resistance. However, after 10 times, the discrete LIG becomenon-conductive.

This is further confirmed by the SEM images of FIGS. 21A-21J, whichshown the effect of the fiber laser on the LIG sheet. After the firstscan (shown in FIGS. 21C-21D), the fiber laser scan only removed the toplayer of LIG resulting in only small change in the sheet as compared tothe original sheet shown in FIGS. 21A-21B (which small change isconsistent with the small change sheet resistance reflected in FIG. 20).The LIG layer after ten times was considerable thin and discrete resultin very high sheet resistance. At ten times of removal (shown in FIGS.21I-21J), the bare PI can be seen in SEM, i.e., FIGS. 21I-21J revealthat, after ten scans, the entire central line of LIG has been removeddown to the polyimide surface. This is consistent with what was seen inthe optical images in FIGS. 19A-19B.

In embodiments of the present invention, gaps in the LIG can be removedwith the laser-induced removal process. For instance, complete removalof the LIG in a gap can be obtained with 15% duty cycle fiber laser of1.06 μm. A laser-induced removal process was utilized to form a 1 cm gapcreated by line pattern and 100 μm width pattern. A pattern of a line of100 μm width was made 1 cm long as a gap between LIG. The gap increasedresistance between two LIG portions separated by this gap. FIG. 22 is agraph showing sheet resistance of this LIG material with plots 2201-2201corresponding, respectively, to the line pattern and 100 μm widthpattern. As shown in FIG. 22, increased resistance was created by thetwo gaps with increased number of removing laser-induced removal scans.

FIGS. 23A-23B are SEM images of this LIG material having, respectively,a line pattern and 100 μm width pattern after ten removal scans. Fromthe SEM images, it was determined that the gap width created by the linepattern is the, which is the thinnest gap that can be made by fiberlaser. The resistance of the gap is basically the resistance of PIitself. Precise gap widths can thus be made by calibrating the computerpattern 40 μm less than desired gap width.

To further confirm this “R” letters from LIG on a PI substrate weregenerated by three different approaches. FIGS. 24A-24B are images of “R”letters made by a normal laser scribing LIG process with a 10.6 μm laserinteracting with a PI film in the shape of the letters “R”. FIGS.24C-24D are images of “R” letters made by starting with the entire areacoated by LIG and then selectively removing LIG regions using the 1.06μm laser to have the letters “R” shown directly on the PI basesurrounded by LIG. FIGS. 24E-24F are “R” letters made from LIG, whichwere made by first coating the entire surface with LIG using the 10.6 μmlaser, then removing most of the surrounding LIG using the 1.06 μm fiberlaser.

This process thus provides improved resolution and control. The abilityto remove the conductive LIG and change it back to insulator if desiredadds enormously to the control of the LIG protocol. In this process, theresolution of the fiber laser is much higher than CO₂ laser (by at leastan order of magnitude). Therefore, precise LIG patterning withmicron-scale resolution can be attainable with this technique. Forinstance, micro-supercapacitor performance can be improved using smallergaps available by fiber laser for electrode separation.

Implementations of this laser-induced removal process also include:

Precise removal thickness can be accomplished by optimizing lasercondition.

Thinner gap can be fabricated with better fiber laser optics.

Use of shorter wavelength lasers for more selective etching.

Different laser wavelengths can be used for this removal process. Justas multiple wavelengths laser can be used to make LIG from multipledifferent starting polymers, multiple lasers can be used to remove LIG,including lasers having wavelengths other than 1.06 μm.

For instance, the starting polymer can be selected from a groupconsisting of polymer films, polymer fibers, polymer monoliths, polymerpowders, polymer blocks, optically transparent polymers, homopolymers,vinyl polymers, chain-growth polymers, step-growth polymers,condensation polymers, random polymers, ladder polymers, semi-ladderpolymers, block co-polymers, carbonized polymers, aromatic polymers,cyclic polymers, doped polymers, polyimide (PI), polyetherimide (PEI),polyether ether ketone (PEEK), polyamide (PA), polybenzoxazole (PBO),polyaramids, and polymer composites and combinations thereof.

The thickness of the polyimide (or other materials utilized when formingthe LIG) can be varied.

The LIG can vary in thickness and density.

The laser-induced removal process can vary in depth and width.

The laser-induced removal process can be utilized on LIGS.

3D Printing of LIG and LIGS Using LOM Process

2D graphene cannot meet the mass and volume demands of current-dayenergy storage devices nor sustain exceptional electrical propertiesunder intense mechanical stress. Thus, in order to pursue high mass andvolume demanding applications, it is necessary to integrate theproperties of 2D graphene into macroscopic, three-dimensional (3D)structures.

Several different prior art methods have been developed to produce 3Dgraphene macrostructures, dubbed graphene foams (GF). The currentfabrication process of graphene foam can be categorized in one of twocategories: (1) growth of graphene in porous metal foam and (2) printingand reduction of graphene oxide (GO) dispersion. The former method usesmetal foam as the growth substrate to grow monolayer or few-layersgraphene on the surface of the porous foam. Then the metal is etched inaqueous solution. In that case, the shape of the graphene foam isdefined by the original metal foam. The latter method used concentratedGO dispersion as overhead printing material; the printed samples werethen freeze dried and reduced to rGO foam.

Embodiments of the present invention further include processes for 3Dprinting of LIG and LIGS using a laminated object manufacturing (LOM)process. LOM is a rapid prototyping system. In general terms, in a LOMprocess, layers of adhesive-coated paper, plastic, metal laminates, orother materials, are successively adhered together and cut to shape,such as with a knife or laser cutter. 3D objects printed with thistechnique may be additionally modified, such as by machining or drillingafter printing. Embodiments of the present invention is an LOM processthat can be utilized to fabricate layer by layer to build up grapheneobjects in a printing mode operation Inventors of the present inventionbelieve that the present invention is the first known process that canbe utilized to 3D print graphene objects.

LIG and LIGS can be utilized alone or in combination in the presentinvention. Such LIG and LIGS can be those materials described above, aswell as the materials described in Lin 2014, the Tour '351 PCTapplication, and the Tour '060 PCT application.

For instance, in embodiments of the present invention, a laser system(Universal laser system XLS10MWH) was utilized with the substrate beingcommercial Kapton Polyimide sheet, 0.005 inch thickness. The printinglayer was a thin commercial Kapton Polyimide sheet, with 0.001 inchthickness for the LIG and commercial Kapton Polyimide sheet, 0.005 inchthickness for the LIGS. The laser parameters were 75 W 10.6 μm laseroperating at 3 kHz and varying duty cycle according to the process with500 pulses/inch image density and patterning speed of 6 inches/sec.

FIG. 25A is schematic of a 3D printing process 2500 of the presentinvention. While the 3D printing process 2500 can be used for LIG andLIGS, individually or in combination, the process will first bedescribed with respect to LIG.

In step 2501, a pre-LIG substrate 2507 is selected (such as polyimidesubstrate).

In step 2502, a laser is used to generate LIG 2508 on one side ofsubstrate 2507. For instance, the printing polyimide substrate ispre-LIG with one side with 0% duty cycle and is LIG with 2% duty cycle.This first layer is laid out as a foundation or base.

In step 2503, a wetting liquid 2509 (such as ethylene glycol/water at a1:4 ratio) is used to wet the LIG 2508 on the one side of substrate2507.

In step 2504, a second substrate 2510 (such as a thin polyimidesubstrate, e.g., as described above) that has a thin layer of LIG 2511are then brought into contact with sides having the LIG 2508 and the LIG2511 facing one another (i.e., the LIG 2508 and the LIG 2511 are broughtinto contact with each other). This can be done by hand or by anautomated process.

In step 2505, a laser is refocused on the other side of the secondsubstrate 2510 (i.e., the side opposite the side with the thin layer ofLIG 2511). The lasering of step 2505 can be performed, for example forLIG, with a 2% duty cycle.

The role of the wetting liquid 2509 is to adhere the LIG 2508 and thethin layer of LIG 2511 to each other and to protect the LIG 2508 fromexcessive laser. Ethylene glycol can be used as the binding agent due toits ease of wetting the LIG 2508, acting as an adhesive throughcapillary force between layers, as well as its high boiling point so itcan protect the LIG from the excessive lasing.

From this step 2505, the resulting thicker LIG 2512 is now formed onsubstrate 2507. I.e., the sandwiched layers are then lased, fusingtogether the LIG sheets. Such step is referred to as adding a layer ofthe LIG.

In step 2506, the substrate 2507 having LIG 2512 is then returned tostep 2503 and the process is then repeated to add additional layers ofLIG.

In some embodiments no wetting liquid 2509 is needed to adhere the firstand second substrates, so step 2503 can be eliminated. In such case, theprocess goes from step 2502 directly to step 2504, and, in step 2506,the substrate is then returned to step 2504 for adding additionallayers.

In some embodiments, the second substrate 2510 is a thin precursorgraphene material that does not have LIG (or LIGS). The second substrate2510 is then adhered to the substrate 2507 (on the side with LIG 2508)and then the process is performed.

It should be noted that, for LIG, utilizing a duty cycle greater than 2%will generally mill the LIG, and utilizing a duty cycle lower than 1.5%or a defocused laser will typically result in layer of LIG that will notproperly adhere to the other LIG substrate.

Furthermore, to evaporate the wetting liquid (such as after the LOMprocess is complete or during an intermediary stage), the printed LIGcan be is annealed, such as 170° C. for 30 minutes in air.

An embodiment of an automated LOM system that interfaces with a lasersystem is shown in FIGS. 26A-26C. The automated LOM system includes of asample platform 2601 attached to a linear stage 2602 in z-axis driven bya stepper motor 2603 (located inside the box), rollers 2604 to feedPFLIG layers 2605, and a control board 2606 (such as an Arduino controlboard), which is attached to, and drives, the stepper motor 2603.

The automated LOM process of the system shown in FIGS. 26A-26C is:

-   -   (1) A roll of PI with LIG embedded is made with the LIG pattern        equally spaced apart.    -   (2) Base LIG is made manually and placed on the sample platform.    -   (3) The roll of LIG-embedded PI is coated with ethylene glycol        and fed into the roller.    -   (4) The platform is raised so the roll is sandwiched to the        base.    -   (5) The laser focuses and is applied to the sandwiched PI.    -   (6) After the layer is completely converted to LIG, the platform        is lower by z-axis linear stage, the roller moves to the next        pattern, and the platform is raised to a new height, adjusting        to the new 3D structure.    -   (7) The laser starts again and repeats the automation to desire        layer number.

3D LIG and 3D LIGS

Referring to FIGS. 25B-25J, 3D LIG was prepared from three increasingthicknesses of PI films (25.4 μm, 50.8 μm, and 128 μm) and the differentLIG structure was analyzed for each thickness. With the thinnest PI(25.4 μm), the converted LIG had a graphitic, sheet-like structure,similar to previously 2D LIG structures. See FIG. 25B. Use of thethickest PI (128 μm) resulted in LIGS dominated morphology, indicated bythe fibrous structure. See FIG. 25C. The middle thickness PI (50.8 μm)resulted in a hybrid LIG/LIGS structure, where there were short butfibrous structures.

The three different PI thicknesses also resulted in increasingthicknesses of resultant structures. FIG. 25D shows that the thicker PIgenerated thicker structure per layer. Per plots 2513-2515 (forincreasing thickness by layers for the 25.4 μm PI, 50.8 μm PI, and 128μm PI, respectively) the increase of thickness per layer was (a) ˜130 μmfor the 25.4 μm PI, (b) ˜150 μm for the 50.8 μm PI, and (c) ˜350 μm forthe 128 μm PI. (For 256 μm PI, thicker formation of LIGS could not bemade since the laser consumes the printed LIGS product quicker than thelaser conversion of PI into LIGS).

To further confirm the graphitic structure of 3D printed LIG and LIGS,TEM and Raman are employed, which are shown in FIGS. 25E-25I. In the TEMimages of FIG. 25E-25F, LIG and LIGS were respectively observed withsheet-like structure and fibrous structure that agree well with thecorresponding SEM images of FIGS. 25B-25C. In FIG. 25G, the Ramanspectra show strong 2D peak with high D/G ratio, indicating the graphenestructure with defects.

The HRTEM image of FIG. 25H shows that the LIG structure is full offolds. The HRTEM image of FIG. 25I shows that LIGS has a graphiticordered or “scroll-like” structure that agrees with the SEM image ofFIG. 25C.

Purity of the printed LIG was analyzed using thermal gravimetricanalysis. In FIG. 25J, there was no dip at ˜200° C. or ˜700° C., whichindicates neither the presence of ethylene glycol nor PI was left in theLIG. XPS showed a high content of N and O doping from vaporized ethyleneglycol in 3D LIG and higher in 3D LIGS.

FIGS. 27A-27E are SEM images of cross-sections of 3D printed LIG with,respectively, 1-5 3D printed layers (utilizing the LOM process describedabove). Each of these layers added approximately 130 which is shown bythe slope of plot 2701 in FIG. 27F. As shown in FIG. 28A, with ninelayers, the 3D printed LIG was able to achieve a thickness of greaterthan 1 mm. FIG. 28B reflects that the LIG of this 3D printed LIGmaintained its porous structure.

As discussed above, the 3D printing process 2500 can also be usedutilizing LIGS alternatively or in addition to LIG. For example, forLIGS, the process 2500 can be the same as described above with thefollowing changes:

The scheme process 2500 with LIGS only with different laser parameter.

Printing polyimide substrate 2507 is pre-LIGS on one side with 10% dutycycle.

The polyimide substrate 2507 is LIGS with 11% duty cycle.

The laser is refocused on the other side of the thin substrate 2510 andthe thin layer of LIGS 2511 with an 11% duty cycle.

It should also be noted that, for LIGS, a duty cycle greater than 15%will mill the LIGS, and utilizing a duty cycle lower than 10% or adefocused laser will typically result in layer of LIGS that will notproperly adhere to the other LIGS substrate.

FIGS. 29A-29E are SEM images of cross-sections of 3D printed LIGS with,respectively, 1-5 3D printed layers (utilizing the LOM process describedabove). Each of these layers added approximately 250 μm (to an originalapproximate 500 μm base), which is shown by the slope of plot 2901 inFIG. 29F. As shown in FIG. 30A the 3D structure of LIGS includedvertical growth of LIGS bundles supporting each other. FIG. 30B reflectsthat the LIGS of this 3D printed LIGS maintained its original porousstructure.

Mechanical Properties

The mechanical properties of the LIG and LIGS produced from the 3Dprinting process was analyzed. Upon drying the LIG showed no perceptibleshrinkage and was free-standing even with a porosity of 98%. The LIGcould be picked up with tweezers without breaking and was flexible evenwhen large and thin.

Using such process to print 3D LIGS, a 5×5×4 mm LIGS cube wasfabricated. The mass, density, and porosity of this LIGS cubes was ˜2.7mg, ˜30 mg/cm³, and ˜1.3%, respectively. FIGS. 31A-31E are opticalimages taken during a stress test for the LIGS cube. As shown in FIGS.31A-31C, upon application of a 20 kPa (50 g) weight, there was little tono deformation, i.e., after the 20 kPa was applied and removed, the LIGScube returned to its original shape. As shown in FIGS. 31D-31E, uponapplication and removal of a 40 kPa (100 g) weight, the cube hadpermanent deformation, which was approximately 1 mm of permanentcompression in the same direction as the applied forces.

As shown in FIG. 31F, after the first cycle of the compression test(plot 3101), the LIG reshaped itself in the compressing direction. Fromthe second cycle (plot 3102) and thereafter, every cycle had the sameshape. This indicated good elasticity property with the elastic modulusof 0.4 MPa. Compared to other graphene foams from CVD or GO printing,this elastic modulus number is quite superior.

Thus the 3D printing process of the present invention was shown tomaintain the high porosity and stable mechanical properties of the LIGand LIGS.

Coupling Process with Laser Removal/Milling Processes

The LOM manufacturing process of the present invention is robust andallows for complex cross-sectional geometries to be printed. Moreover,the process to make 3D objects from LIG and LIGS can be further improvedby combining it with the different approaches to form 3D objectsdiscussed above with respect to FIGS. 23A-23F above, including thelaser-induced removal of LIG described above. Such laser-induced removalof LIG or other milling techniques can be used for example to addressthe edge of printed LIG patterns that may have relatively poorresolution.

For high resolution of printing, fiber lasing was employed to mill (orablate) the bulk LIG produced using the 3D printing process. FIG. 32A isa schematic for the milling with a fiber laser. The fiber laser utilizedhad a 1.06 μm wavelength and peak power of 50 W. As discussed above, LIGhas high absorption at 1.06 μm resulting in the local heating andablation of LIG. However, PI is transparent to 1.06 μm, so the appliedlaser neither destroyed nor carbonized the substrate. Thus, the fiberlaser milled the LIG structure to the desired thickness by tuning theoutput average power.

The fluence and the ablation thickness nearly increased linearly withrespect to each other with the rate of 2.5 μl/J. As shown in FIG. 32B,using the fluence of 6 J/cm², LIG is gradually thinned by multiple lasermilling scans. These results are shown by the Raman spectra of FIG. 32C,which shows that at 5 times of milling, the PI starts to appear and, at10 times milling, the completion of LIG removal is reached.Interestingly, the Raman spectra show no difference between a singleapplication and multiple applications of laser milling. This indicatesthat the fiber laser only locally ablates the LIG while keeping itsdisordered graphene structure.

This 1.06 μm fiber laser has a theoretical resolution limit 10 timesbetter than the 10.6 μm laser. In the system being utilized, the LIGfabricated through the CO₂ laser process had a resolution of ˜75 μm.Both the fiber laser and the CO₂ laser share the same commercial opticsystem that was optimized for the CO₂ laser. To determine the resolutionof the fiber laser, LIG was removed by a single raster line. Aftermultiple laser treatment, the LIG was completely removed, revealing thePI substrate, as shown in FIG. 32D. The width of the line was theresolution of the fiber laser, which was found to be ˜30 μm. Resolutioncan be further focused with adjustment to the optical system.

FIG. 32E is an SEM image of an “R” letter made from 3D LIG with fiberlaser tailoring. FIG. 33 is an optical image of an “R” letter of LIGmade by 3D printing that was combined with precise removal of LIG/LIGSstructure with high resolution.

3D printing of LIG and/or LIGS using a LOM process is important asprevious LIG thickness has been limited to 50 μm. Hence, these 3Dprinting techniques increase the thickness of LIG with availablecommercial methods to build thick 3D objects of any size and shape.Moreover, this process does not require a vacuum or special environmentand can be based upon available commercial materials and systems.

Conductivity

The in-plane conductivity of the 3D LIG was investigated. Platinumcontact pads (200 μm×200 μm) were directly deposited on them using ashadow mask by DC sputter (Desk V sputter system, Denton Vacuum). Theseare shown in FIGS. 34A-34B. 3D LIG that had been fabricated on PIsubstrates with different layer thickness (25, 50, and 125 μm) weremeasured using a semiconductor device analyzer (B1500A, AgilentTechnologies).

The conductivity (σ=I×I/V×A) was calculated from total 30 differentpoints of the sample, where I and A are the distance and cross-sectionalarea between the contact pads, respectively. As shown in plots 3401-3403of FIG. 34C, the average conductivities of the samples with the PIthicknesses of 25, 50, and 125 μm were 0.27±0.15, 0.70±0.20, and0.90±0.19 S cm⁻¹, respectively. This conductivity is comparable to othergraphene aerogels that fabricated specifically for high conductivity.

Performance

The 3D LIG performance was tested as a lithium ion supercapacitor (LIC)electrode. The electrochemical characterizations of LIG electrodes asLi-ion capacitors were made using 2032 coin cells for the half-cells (Lifoil used as reference and counter electrode). The cells were testedusing a MTI Battery Analyzer. Electrodes were prepared from 3D LIGfoams, without the use of binders or current collectors. Celgard 2400membranes were used as separators and 1.0 M LiPF₆ (lithiumhexafluorophosphate) in a mixture 50/50 (v/v) of ethylenecarbonate:diethyl carbonate (EC:DEC) as the electrolyte. The half cellswere tested between 1 and 4.3 V for the cathode and 0.01 and 3 V for theanode. All the cells were assembled in a Ar-filled glovebox with O₂ andH₂O content below 2 ppm. To assemble the full supercapacitor, 3D LIGanode and cathode with mass ratio of 5.6:1 were selected.

As shown in FIGS. 35A-35B, the anode shows the average capacity close tothe theoretical capacity of graphite of 372 mAh/g. Both anode andcathode show stable retention and reversible Li storage.

PDMS/LIG and PDMS/LIGS Composite

Graphene/polymer composite has many potential applications. The presentinvention further includes composites of a polymer with one or both ofLIG and LIGS. A 3D LIG/PDMS composite was fabricated by pouring uncuredsilicone elastomer and curing agent on top of the LIG. The uncuredmixture wet the LIG well. To remove the air inside the LIG, the samplewas put inside a vacuum chamber and a vacuum was applied. Air bubblesquickly evolved while the elastomer mixture infiltrated the LIG. After 1hour, all of the remaining mixture was drained, and then the compositewas cured at 60° C. overnight. After curing, the 3D LIG was filled withPDMS.

The PDMS/LIG composite maintained the shape of the initial 3D LIG. ThePDMS/LIG composite was cut into a dog-bone shape (as shown in the insetof FIG. 36A) for the stress-strain test. FIG. 36A is an image ofstress-strain testing apparatus for the LIG/PDMS composite.

The results are shown graphically in FIG. 36B with plots 3601-3602 forthe PDMS/LIG composite and PDMS, respectively. These results showed a 7times increasing in elastic modulus. This further reflects that theutility of the present invention fabrication process for direct printingand infiltration of strength-enhanced polymer composite with 3D LIG (andLIGS).

Further Controls for the LOM Process

Implementations of this 3D printing LOM process can also include:

Use of different polymers (such as for stronger structure).

The use of a controlled atmosphere box to adjust/alter the properties ofthe final graphene structures.

The use of other gases in the process, such as O₂, SbF₅, N₂, Ar, H₂, ormixtures thereof.

The use of thicker PI (or other substrates) can be used.

The process can further include lasing the bottom of the applied PI (ornot lasing the bottom), before applying it as the new layer. One canalso alternate between such lasing/non-lasing techniques.

Alternating the process with LIG and LIGS.

Adding carbon nanotubes to the graphene precursor materials. Forexample, carbon nanotubes can be added to the polyimide, which carbonnanotubes can reinforce the 3D printed object. [See Sha 2017 regardingother types of graphene materials].

The starting polymer to make the LIG and LIGS can be selected from agroup consisting of polymer films, polymer fibers, polymer monoliths,polymer powders, polymer blocks, optically transparent polymers,homopolymers, vinyl polymers, chain-growth polymers, step-growthpolymers, condensation polymers, random polymers, ladder polymers,semi-ladder polymers, block co-polymers, carbonized polymers, aromaticpolymers, cyclic polymers, doped polymers, polyimide (PI),polyetherimide (PEI), polyether ether ketone (PEEK), polyamide (PA),polybenzoxazole (PBO), polyaramids, and polymer composites andcombinations thereof. For instance, the polyamide (PA) can be Kevlar(and thus can encompass uses for the resulting LIG and LIGS ofprotection, armor, cryogenics, etc.).

While embodiments of the invention have been shown and described,modifications thereof can be made by one skilled in the art withoutdeparting from the spirit and teachings of the invention. Theembodiments described and the examples provided herein are exemplaryonly, and are not intended to be limiting. Many variations andmodifications of the invention disclosed herein are possible and arewithin the scope of the invention. Accordingly, other embodiments arewithin the scope of the following claims. The scope of protection is notlimited by the description set out above.

The disclosures of all patents, patent applications, and publicationscited herein are hereby incorporated herein by reference in theirentirety, to the extent that they provide exemplary, procedural, orother details supplementary to those set forth herein.

Concentrations, amounts, and other numerical data may be presentedherein in a range format. It is to be understood that such range formatis used merely for convenience and brevity and should be interpretedflexibly to include not only the numerical values explicitly recited asthe limits of the range, but also to include all the individualnumerical values or sub-ranges encompassed within that range as if eachnumerical value and sub-range is explicitly recited. For example, anumerical range of approximately 1 to approximately 4.5 should beinterpreted to include not only the explicitly recited limits of 1 toapproximately 4.5, but also to include individual numerals such as 2, 3,4, and sub-ranges such as 1 to 3, 2 to 4, etc. The same principleapplies to ranges reciting only one numerical value, such as “less thanapproximately 4.5,” which should be interpreted to include all of theabove-recited values and ranges. Further, such an interpretation shouldapply regardless of the breadth of the range or the characteristic beingdescribed.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which the presently disclosed subject matter belongs.Although any methods, devices, and materials similar or equivalent tothose described herein can be used in the practice or testing of thepresently disclosed subject matter, representative methods, devices, andmaterials are now described.

Following long-standing patent law convention, the terms “a” and “an”mean “one or more” when used in this application, including the claims.

Unless otherwise indicated, all numbers expressing quantities ofingredients, reaction conditions, and so forth used in the specificationand claims are to be understood as being modified in all instances bythe term “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in this specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by the presently disclosed subject matter.

As used herein, the term “about,” when referring to a value or to anamount of mass, weight, time, volume, concentration or percentage ismeant to encompass variations of in some embodiments ±20%, in someembodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, insome embodiments ±0.5%, and in some embodiments ±0.1% from the specifiedamount, as such variations are appropriate to perform the disclosedmethod.

As used herein, the term “and/or” when used in the context of a listingof entities, refers to the entities being present singly or incombination. Thus, for example, the phrase “A, B, C, and/or D” includesA, B, C, and D individually, but also includes any and all combinationsand subcombinations of A, B, C, and D.

REFERENCES

-   Allen, M. J. et al. Honeycomb Carbon: A Review of Graphene. Chem.    Rev. 2009, 110, 132-145 (“Allen 2009”).-   Baughman, R. H. et al. Carbon Nanotubes—the Route toward    Applications. Science. 2002, 297, 787-792 (“Baughman 2002”).-   Bonaccorso, F. et al. Graphene, Related Two-Dimensional Crystals,    and Hybrid Systems for Energy Conversion and Storage. Science. 2015,    347 (“Bonaccorso 2015”).-   Cao, Q. et al. Arrays of Single-Walled Carbon Nanotubes with Full    Surface Coverage for High-Performance Electronics. Nat Nano 2013, 8,    180-186 (“Cao 2013”).-   De Volder, M. F. L. et al. Carbon Nanotubes: Present and Future    Commercial Applications. Science. 2013, 339, 535 LP-539 (“De Voider    2013”).-   El-Kady, M. F. et al. Scalable Fabrication of High-Power Graphene    Micro-Supercapacitors for Flexible and on-Chip Energy Storage. Nat.    Commun. 2013, 4, 1475 (“El-Kady 2013”).-   Ferrari, A. Raman Spectroscopy of Graphene and Graphite. Solid State    Commun. 2007, 143, 47-57 (“Ferrari 2007”).-   Ferrari, A. C. et al. Raman Spectrum of Graphene and Graphene    Layers. Phys. Rev. Lett. 2006, 97, 1-4 (“Ferrari 2006”).-   Habisreutinger, S. N. et al. Carbon Nanotube/Polymer Composites as a    Highly Stable Hole Collection Layer in Perovskite Solar Cells. Nano    Lett. 2014, 14, 5561-5568 (“Habisreutinger 2014”).-   Hata, K.; Futaba et al. Water-Assisted Highly Efficient Synthesis of    Impurity-Free Single-Walled Carbon Nanotubes. Science. 2004, 306,    1362-1364 (“Hata 2004”).-   Heinze, S. et al. Carbon Nanotubes as Schottky Barrier Transistors.    Phys. Rev. Lett. 2002, 89, 106801 (“Heinze 2002”).-   Hu, K. et al. Graphene-Polymer Nanocomposites for Structural and    Functional Applications. Prog. Polym. Sci. 2014, 39, 1934-1972 (“Hu    2014”).-   Iijima, S. Helical Microtubules of Graphitic Carbon. Nature 1991,    354, 56-58 (“Iijima 1991”).-   Inagaki, M. et al. Carbonization and Graphitization of Polyimide    Film “Novax.” Carbon N. Y. 1991, 29, 1239-1243 (“Inagaki 1991”).-   Inagaki, M. et al. Carbonization of Polyimide Film “Kapton.”    Carbon N. Y. 1989, 27, 253-257 (“Inagaki 1989”).-   Jariwala, D. et al. Carbon Nanomaterials for Electronics,    Optoelectronics, Photovoltaics, and Sensing. Chem. Soc. Rev. 2013,    42, 2824-2860 (“Jariwala 2013”).-   Kaempgen, M. et al. Printable Thin Film Supercapacitors Using    Single-Walled Carbon Nanotubes. Nano Lett. 2009, 9, 1872-1876    (“Kaempgen 2009”).-   Kosynkin, D. V et al. Longitudinal Unzipping of Carbon Nanotubes to    Form Graphene Nanoribbons. Nature 2009, 458, 872-876 (“Kosynkin    2009”).-   Kroto, H. W. et al. C60: Buckminsterfullerene. Nature 1985, 318,    162-163 (“Kroto 1985”).-   Li, L. et al. High-Performance Pseudocapacitive Microsupercapacitors    from Laser-Induced Graphene. Adv. Mater. 2016, 28, 838-845 (“Li    2016”).-   Li, Y et al. Laser-Induced Graphene in Controlled Atmospheres: From    Superhydrophilic to Superhydrophobic Surfaces. Adv. Mater. 2017,    201700496—n/a (“Li 2017”).-   Lin, J. et al. Laser-Induced Porous Graphene Films from Commercial    Polymers. Nat. Commun. 2014, 5, 1-8 (“Lin 2014”).-   Liu, C.-H. et al. Graphene Photodetectors with Ultra-Broadband and    High Responsivity at Room Temperature. Nat Nano 2014, 9, 273-278    (“Liu 2014”).-   Marcano, D. C. et al. Improved Synthesis of Graphene Oxide. ACS Nano    2010, 4, 4806-4814 (“Marcano 2010”).-   Mittal, G. et al. A Review on Carbon Nanotubes and Graphene as    Fillers in Reinforced Polymer Nanocomposites. J. Ind. Eng. Chem.    2015, 21, 11-25 (“Mittal 2015”).-   Novoselov, A. K. et al. Electric Field Effect in Atomically Thin    Carbon Films. Science. 2013, 666, 666-669 (“Novoselov 2013”).-   Palejwala, A. H. et al. Biocompatibility of Reduced Graphene Oxide    Nanoscaffolds Following Acute Spinal Cord Injury in Rats. Surg.    Neurol. Int. 2016, 7, 75 (“Palejwala 2016”).-   Peng, Z. et al. Flexible and Stackable Laser-Induced Graphene    Supercapacitors. ACS Appl. Mater. Interfaces 2015, 7, 3414-3419    (“Peng 2015 A”).-   Peng, Z. et al. Flexible Boron-Doped Laser Induced Graphene    Microsupercapacitors. ACS Nano 2015, 9, 1-17 (“Peng 2015 B”).-   Ren, J. et al. Twisting Carbon Nanotube Fibers for Both Wire-Shaped    Micro-Supercapacitor and Micro-Battery. Adv. Mater. 2013, 25,    1155-1159 (“Ren 2013”).-   Rodrigo, D. et al. Mid-Infrared Plasmonic Biosensing with Graphene.    Science. 2015, 349, 165 LP-168 (“Rodrigo 2015”).-   Sahni, D. et al. Biocompatibility of Pristine Graphene for Neuronal    Interface J. Neurosurg. Pediatrics. 2013, 11, 575-583 (“Sahni    2013”).-   Scharfman, B. E et al. Visualization of Sneeze Ejecta: Steps of    Fluid Fragmentation Leading to Respiratory Droplets. Exp. Fluids    2016, 57, 1-9 (“Scharfman 2016”).-   Schumann, M. et al. Permanent Increase of the Electrical    Conductivity of Polymers Induced by Ultraviolet Laser Radiation.    Appl. Phys. Lett. 1991, 58, 428-430 (“Schumann 1991”).-   Schwierz, F. Graphene Transistors. Nat. Nanotechnol. 2010, 5,    487-496 (“Schweirz 2010”).-   Sha, J. et al. Three-Dimensional Rebar Graphene. ACS Appl. Mater.    Interf. 2017, 9, 7376-7384 (“Sha 2017”).-   Shao, Y. et al. Graphene Based Electrochemical Sensors and    Biosensors: A Review. Electroanalysis 2010, 22, 1027-1036 (“Shao    2010”).-   Smith, M. K. et al. Thermal Conductivity Enhancement of Laser    Induced Graphene Foam upon P3HT Infiltration. Appl. Phys. Lett.    2016, 109, 253107 (“Smith 2016”).-   Srinivasan et al. Ultraviolet Laser Irradiation of the Polyimide,    PMDA-ODA (Kapton™), to Yield a Patternable, Porous, Electrically    Conducting Carbon Network. Synth. Met. 1994, 66, 301-307    (“Srinivasan 1994”).-   Sun, Z. et al. Large-Area Bernal-Stacked Bi-, Tri-, and Tetralayer    Graphene. ACS Nano 2012, 6, 9790-9796 (“Sun 2012”).-   Yan, Z. et al. Toward the Synthesis of Wafer-Scale Single-Crystal    Graphene on Copper Foils. ACS Nano 2012, 6, 9110-9117 (“Yan 2012”).-   Yan, Z. et al. Growth of Bilayer Graphene on Insulating Substrates.    ACS Nano 2011, 5, 8187-8192 (“Yan 2011”).-   Ye, R. et al. In Situ Formation of Metal Oxide Nanocrystals Embedded    in Laser-Induced Graphene. ACS Nano 2015, 9, 9244-9251 (“Ye 2015”).-   Yoo, E. et al. Large Reversible Li Storage of Graphene Nanosheet    Families for Use in Rechargeable Lithium Ion Batteries. Nano Lett.    2008, 8, 2277-2282 (“Yoo 2008”).-   Zhang, Y. et al. Review of Chemical Vapor Deposition of Graphene and    Related Applications. Acc. Chem. Res. 2013, 46, 2329-2339 (“Zhang    2013”).

1-59. (canceled)
 60. A method comprising: (a) selecting a laser-inducematerial selected from a group consisting of laser-induced graphene(LIG) materials, laser-induced graphene scrolls (LIGS) materials, andcombinations thereof (LIG/LIGS materials); and (b) exposing thelaser-induced material to a first laser source having a first wavelengthto remove a first portion of LIG or LIGS from the laser-inducedmaterial. 61-69. (canceled)
 70. The method of claim 60, wherein thelaser-induce material comprises a LIG material.
 71. The method of claim60, wherein the laser-induce material comprises a LIGS material.
 72. Themethod of claim 60, wherein the laser-induce material comprises acomposite LIG/LIGS material.
 73. The method of claim 60, wherein themethod forms a 3D object. 74-75. (canceled)
 76. The method of claim 60,wherein (a) the laser induced material was formed by exposing a grapheneprecursor material to a second laser source having a second wavelength;(b) the first wavelength and the second wavelength are different; and(c) the graphene precursor material comprises a polymer.
 77. The methodof claim 76, wherein the polymer is selected from a group consisting ofpolymer films, polymer fibers, polymer monoliths, polymer powders,polymer blocks, optically transparent polymers, homopolymers, vinylpolymers, chain-growth polymers, step-growth polymers, condensationpolymers, random polymers, ladder polymers, semi-ladder polymers, blockco-polymers, carbonized polymers, aromatic polymers, cyclic polymers,doped polymers, polyimide (PI), polyetherimide (PEI), polyether etherketone (PEEK), polyamide (PA), polybenzoxazole (PBO), polyaramids, andpolymer composites and combinations thereof.
 78. The method of claim 60further comprising a step of incorporating the laser-induced materialinto an electronic device, after the step of exposing the laser-inducedmaterial to the first laser source. 79-80. (canceled)
 81. A method toproduce an object, wherein (a) the method is a laminated objectmanufacturing process; and (b) the object is a LIG, LIGS, or LIG/LIGSobject.
 82. A method comprising: (a) selecting a first substrate havinga first laser-induce material disposed on a first side of the firstsubstrate, wherein (i) the first substrate is a first graphene precursormaterial that can be formed in to the first laser-induced material, and(ii) the first laser-induced material is selected from a groupconsisting of laser-induced graphene (LIG), laser-induced graphenescrolls (LIGS) materials, and combinations thereof (LIG/LIGS); (b)selecting a second substrate having a first side and a second side,wherein (i) the second substrate is a second graphene precursor materialthat can be formed in to a second laser-induced material, and (ii) thesecond laser-induced material is selected from a group consisting ofLIG, LIGS, and LIG/LIGS; (c) contacting the first laser-induced materialon the first side of the first substrate with the first side of thesecond substrate; and (d) exposing the second side of the secondsubstrate to a first laser source to form a layer of the secondlaser-induced material upon the first laser-induced material.
 83. Themethod of claim 82, wherein, before contacting the first laser-inducedmaterial to the first side of the second substrate, the method furthercomprises a step of depositing a wetting liquid on one or both of (i)the first laser-induced material on the first side of the firstsubstrate and (ii) the first side of the second substrate. 84-85.(canceled)
 86. The method of claim 82, wherein the method is a laminatedobject manufacturing process.
 87. The method of claim 82, wherein thestep of selecting a first substrate having a first laser-induce materialdisposed on a first side of the first substrate comprises selecting thefirst substrate and exposing the first substrate to a second lasersource to form the first laser-induce material disposed on the firstside of the first substrate. 88-91. (canceled)
 92. The method of claim82, wherein the steps (b)-(d) are repeated to form additional layers.93. (canceled)
 94. The method of claim 82, wherein (a) the firstgraphene precursor material is a first polymer; (b) the second grapheneprecursor material is a second polymer; and (c) the first polymer andthe second polymer are the same polymer or different polymers.
 95. Themethod of claim 94, wherein each of the first polymer and the secondpolymer are selected from a group consisting of polymer films, polymerfibers, polymer monoliths, polymer powders, polymer blocks, opticallytransparent polymers, homopolymers, vinyl polymers, chain-growthpolymers, step-growth polymers, condensation polymers, random polymers,ladder polymers, semi-ladder polymers, block co-polymers, carbonizedpolymers, aromatic polymers, cyclic polymers, doped polymers, polyimide(PI), polyetherimide (PEI), polyether ether ketone (PEEK), polyamide(PA), polybenzoxazole (PBO), polyaramids, and polymer composites andcombinations thereof. 96-99. (canceled)
 100. The method of claim 83further comprising a step of annealing to remove the wetting liquid.101-102. (canceled)
 103. The method of claim 82, wherein the methodfabricates a 3D graphene object.
 104. The method of claim 103, whereinthe 3D graphene object has a thickness of at least 1 mm.
 105. The methodof claim 103, wherein the 3D graphene object has a mass of at leastabout 3.5 mg and a porosity of at least about 1.3%.
 106. The method ofclaim 105, wherein the 3D graphene object is capable of having a 20 kPastress applied in a first direction without any permanent deformation ofthe 3D graphene object. 107-109. (canceled)
 110. The method of claim103, wherein the 3D object is selected from the group consisting ofmechanical dampeners, conducive mechanical dampeners, heat conductionblocks, lightweight conductive blocks, templates for growth ofbiological cells, and composites for bone and neuron growth.
 111. Themethod of claim 110, wherein the biological cells are eukaryote or plantcells.
 112. The method of claim 103 further comprising a step ofincorporating the 3D graphene object into an electronic device.
 113. Themethod of claim 112, wherein the electronic device is selected from agroup consisting of super capacitors, micro-supercapacitors, pseudocapacitors, batteries, micro batteries, lithium-ion batteries,sodium-ion batteries, magnesium-ion batteries, electrodes, conductiveelectrodes, sensors, lithium ion capacitors, photovoltaic devices,electronic circuits, fuel cell devices, thermal management devices,biomedical devices, and combinations thereof.
 114. The method of claim112, wherein the electronic device is a micro-supercapacitor. 115-117.(canceled)
 118. A method to form a 3D object comprising: (a) performinga first process to make a laser-induced material, wherein the firstprocess comprises (i) selecting a first substrate having a firstlaser-induce material disposed on a first side of the first substrate,wherein (A) the first substrate is a first graphene precursor materialthat can be formed in to the first laser-induced material, and (B) thefirst laser-induced material is selected from a group consisting oflaser-induced graphene (LIG), laser-induced graphene scrolls (LIGS)materials, and combinations thereof (LIG/LIGS); (ii) selecting a secondsubstrate having a first side and a second side, wherein (A) the secondsubstrate is a second graphene precursor material that can be formed into a second laser-induced material, and (B) the second laser-inducedmaterial is selected from a group consisting of LIG, LIGS, and LIG/LIGS;(iii) contacting the first laser-induced material on the first side ofthe first substrate with the first side of the second substrate; and(iv) exposing the second side of the second substrate to a first lasersource to form a layer of the second laser-induced material upon thefirst laser-induced material; and (b) performing a second process toremove a first portion of LIG or LIGS from the laser-induced material,wherein the second process comprises (i) selecting the laser-inducematerial made by the first process, wherein the laser-induced materialis selected from a group consisting of laser-induced graphene (LIG)materials, laser-induced graphene scrolls (LIGS) materials, andcombinations thereof (LIG/LIGS materials); and (ii) exposing thelaser-induced material to a second laser source having a firstwavelength to remove the first portion of LIG or LIGS from thelaser-induced material. 119-120. (canceled)
 121. The method of claim 118further comprising a step of incorporating the 3D object into anelectronic device. 122-123. (canceled)
 124. The method of claim 81,wherein the object is a 3D LIG object.
 125. The method of claim 81,wherein the object is a 3D LIGS object.
 126. The method of claim 81,wherein the object is a 3D LIG/LIGS object.